The code will only work if I take out 'parseInt()' command...

The parseInt method takes a response and turns it into an int, which is the datatype used to represent numbers. This is a good practice to do if you are working with numbers but it can cause issues if:

1. The answer is not stored as an int but as a string, in other words you use quotes when defining the number.
2. The answer is not actually a number, but a word or sentence.

In the first case since the answer is stored in a string and the response is stored as an int they will fail the type equality test that the === operator enforces, and therefore appear unequal even if the number are in fact the same. In the second case parseInt will convert the response into a value known as NaN (Not a Number) since the response it is asked to convert is in fact not a number.

Looking at your code I see that your questions fit point 1. I recommend changing the answers into pure numbers, in other words store them as 50 and not '50' and the like. If you decide to add questions that have words as answer then not using parseInt is in fact the right thing to do.