The correct option is
A ABBAA
The apostrophe should be before the 's' hence option A is correct.
We 'look into' something but we investigate something hence B is correct.
In sentence 2 option B is correct because we should use 'do' in a positive clause only when we wish to expressemphasis. For example. 'I do like these fruits.'
In sentence 3 'more' should not befollowed by 'of' hence option A is acceptable.
In sentence 4 since the first clause begins with a conjunction (if), the next clause cannot begin with so. Hence ABBAA is correct.