Firstly, put the lineUseNewDefaultFonts(1) near the top of your code. It will make the font look much nicer.
Secondly, if this app is meant for learning English then you really should use correct English in it. Nobody says "the Jupiter" or "the Mercury". You could get away with "the Earth" but equally you could drop "the" for all of them. Realistically though, if it were me, I would also drop "This is" from the answers and just offer "Jupiter, Mercury, Earth"
[EDIT]I've just tried it. I'm guessing English isn't your first language, so maybe this is an odd choice of app for you.
The first question:
She .... English in her room
1. was studying
2. has been studying
3. is studying
All three of those are are perfectly acceptable.
Hi, my name is James
1. Hi. James.
3. Let's go.
Again, all three are perfectly acceptable responses (almost), the first one has a full stop after "Hi" which makes it wrong and yet that is the answer you have chosen to be correct.
The third question required audio which I don't have so I had to stop there.