Tom maintained that his scholastic record was better or at least as go

This one is testing the idiomatic structure of common comparisons. Your main comparison structures are:

1) Better than / greater than / taller than / faster than, etc. Basically if you have an -er comparative adjective, you want to find a "than" to complete the structure. (Also note that less than, worse than, etc. fit this...it doesn't *have* to have an -er but most do)

2) As many as / as much as / as good as / as bad as, etc. Basically if you start a comparison with "as" you need to finish it with "as" - it either shows equality (I have as much money as you do) or it can show orders of magnitude (Jeff Bezos has 100,000 times as much money as I do)

3) Tall compared to / fast compared to, etc. If you want to use "compared to" you can only use a simple adjective, not a comparative adjective. You can say that I'm tall compared to my wife because I may or may not be tall, but in the context of comparing me to her I am. If you say "taller compared to" that's redundant - "compared to" and "-er" both express that a comparison is being drawn.

Now...in this case there are really two comparison structures, #1 ("better than") and #2 ("as good as"). Note that (A), (C), and (D) each omit a "closing" word of one of the two comparisons - you're either missing a second "as" to complete "as good as" or you're missing the "than" that needs to be paired with "better." And then (B) uses a strange meaning...to say "its scholastic record at its least" puts a strange quantifier on "scholastic record" at a specific point in time, but you're then not doing that with "hers." Plus scholastic record isn't really a numerical item...if you said "GPA" you'd be able to say "at its least" (grade point average is a number that changes over time) but you'd still need to put a time frame on hers (e.g. "than hers at its best") to have a parallel comparison.