Your first match
One more fact ties the last lesson together: r0 is where a function's return value lives. Whatever sits in r0 when bx lr runs is what the caller receives.
So a function that returns a constant has almost nothing to do. Drop the number into r0, return. Here is one that hands back seven:
0 mov r0, #7
2 bx lr
Written in C, that is simply:
s32 answer7(void) {
return 7;
}
(s32 is this course's name for a signed 32-bit integer. Real GBA projects use s8/u8/s16/u16/s32/u32 names everywhere rather than int and short, so this course does too. They are already defined for you in every exercise.)
Your task
Your target uses a different number, so read the Target asm panel and write the C. Hit Compile & Check (or ⌘/Ctrl + Enter) to see how you did.