D is the best answer because "Mom" is capitalized only when it's used as if it's the mother's name. When referring to "a mom" or "your mom" or "Tasha's mom," it's just a noun like any other; you wouldn't say "a Table" or "your Table" or "Tasha's Table," would you? So A is wrong because "Your Mom" is erroneously capitalized; B is wrong because "mom" was lowercase once when it was used to represent her name; and C is wrong because "my Mom" should be lowercase.