... chess playing CAUSES increase in academic performance. Basically; some major paraphrasing ...
C) says the increased academic performance (Y) of the children ...
... program contributed to the students' academic achievement in other areas because ... the chess program saw improved academic achievement because after doing the ... alternative reason for their improved academic performance.
You really should have at least two academic if you can. You're not K-JD but you aren't far off so I would say your best bet is two academic LORs and one from your employer.
Also it doesn't matter if the UG prof was in a law related class. Just get the best second academic LOR you can regardless of the area of expertise of the professor, or the class you took with them.
There are only two real rules: answer the prompt and don't be boring. If contractions work then go for it. This isn't an academic paper or one that would otherwise require such formality.