This isn’t parallel, because the rule presented applies to comparisons for oneself, but doesn’t hold across comparisons between different people. As “one” gets older, “one” gets wiser — so we could say that the same person when older is wiser than she was when younger. But it doesn’t allow us to conclude Henrietta is wiser than her daughter.

This isn’t parallel, because there are two qualities (more egg whites and longer they are beaten) that are associated with fluffier meringue, and we don’t know about the second quality for Lydia.

This doesn’t involve a “the more X, the more Y” rule.

We get a rule that the more X, the more Y (the older a tree, the more rings it has). Then, (D) applies that rule to a specific case. L has more X than T, so L has more Y than T.

(Note that this answer is different from (A), because “the older a tree, the more rings it has” can be applied to a comparison between different trees, whereas “the older ONE is, the wiser ONE is” can’t be applied to a comparison between different people.)

This reverses the direction when applying the rule. Rather than going from something with more X to more Y, the application goes from something with more Y to more X. So it’s not parallel.