// For theory
function changeColorB1() {
    document.getElementById('btn1').className = "btn btn-danger";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-primary";
}

function changeColorB2() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-danger";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-primary";    
}

function changeColorB3() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-danger";
    document.getElementById('btn4').className = "btn btn-primary";    
}

function changeColorB4() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-danger";    
}

// For experiment

function changeColorE1() {
    document.getElementById('btn1').className = "btn btn-danger";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-primary";
    document.getElementById('btn5').className = "btn btn-primary";
}

function changeColorE2() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-danger";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-primary";
    document.getElementById('btn5').className = "btn btn-primary";
}
 
function changeColorE3() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-danger";
    document.getElementById('btn4').className = "btn btn-primary";
    document.getElementById('btn5').className = "btn btn-primary";
}

function changeColorE4() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-danger";
    document.getElementById('btn5').className = "btn btn-primary";
}

function changeColorE5() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
    document.getElementById('btn4').className = "btn btn-primary";
    document.getElementById('btn5').className = "btn btn-danger";
}

// For quiz

function changeColorQ1() {
    document.getElementById('btn1').className = "btn btn-danger";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-primary";
}

function changeColorQ2() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-danger";
    document.getElementById('btn3').className = "btn btn-primary";
}

function changeColorQ3() {
    document.getElementById('btn1').className = "btn btn-primary";
    document.getElementById('btn2').className = "btn btn-primary";
    document.getElementById('btn3').className = "btn btn-danger";
}