QUIZZ APP BUG: run time error attemp to get number 4 of a list length 3 (A B C)

Hey guys, im doing a quizz app which users can upload their question, number of question (tongsocau in my code) and the answer of each question as type A A B C (1.A 2.A 3.B 4.C) but i have some bugs when i test it, i have tried to fix it and it still like that i have no more idea please help
here is some translate of variable names:
dapan: correct answer (user input it
Diem: mark,point
tongsocau: total question (user input it)
câu: question number


Try this extension for quiz

You are using an index of 4 for a list of length 3, probably here:

tongsocau is longer than the answers or dapan list

but i create answer by length of tongsocau, so tongsocau=answer.
but is dapan equal to too? cause i use in put A A A A as a text, use split as spaces to create dapan list so it should be all equal to, how can it not

is my split text code right?
i want to split a string A B C D to a list dapan[1]=“A”, dapan[2]=“B”,…

I’m not sure, I can’t go through your blocks at the moment but while running your quiz app on companion, use the do it function to check which select list item block causes the error. You will find it quickly.