This is the most tempting wrong answer because every piece seems to line up: "as one gets older one gets wiser" looks like the rule, "Henrietta is older than her daughter" looks like the comparison, and "Henrietta must be wiser" looks like the conclusion applying the rule. But look carefully at how the rule is worded. "As one gets older one gets wiser" is a claim about a single person over time. It says that you become wiser as you age. It doesn't say that any older person is wiser than any younger person. Henrietta might be wiser now than she was ten years ago, but that doesn't mean she's wiser than her daughter.

Compare this to the stimulus, where the rule applies across different things: higher altitude means thinner air, whether we're comparing two cities, two mountains, or anything else. The rule in (A) doesn't work that way.

To see the difference clearly: if (A) had said "the older the person, the wiser," it would match the stimulus, because that rule applies across different people.

And if the stimulus had said "as a city gets higher in altitude, its air gets thinner," it would match (A), because that rule would apply to a single city changing over time, not to a comparison between two different cities.

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 how this differs from (A). "The older a tree, the more rings it has" applies across different trees. "As one gets older one gets wiser" applies to a single person over time. That's what makes (D) parallel to the stimulus and (A) not.)

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.