No flaw. (A) gives us a conditional statement with two variables in the necessary condition. It then validly concludes that the presence of the sufficient condition (the recipe turning out) and part of the necessary condition (following the recipe exactly) will lead to the remaining part of the necessary condition (high-quality ingredients). The stimulus, however, features an incorrect reading of a conditional statement with two variables in the sufficient condition, so (A) doesn’t match.

Wrong flaw. (B) does give us a conditional statement with two variables in the sufficient condition, but the necessary condition is not met. We need to know that Aletha’s needs were met this year, not last year. The stimulus, meanwhile, concludes that the presence of a necessary condition leads to the sufficient condition, so (B) doesn’t match.

The argument starts by establishing a conditional relationship with a conjunction in the sufficient condition. It then concludes that part of the sufficient condition must be present (watered more than twice weekly) because the necessary condition (the cactus dying) and the other part of the sufficient condition (kept in the shade) are met. The stimulus also concludes that part of a sufficient condition is met because the necessary condition and the other part of the sufficient condition are met, so (C) matches.

No flaw. (D) establishes a conditional relationship: if dry rot and poor drainage, then near a high water table. It then correctly concludes that the presence of both parts of the sufficient condition leads to the necessary condition. The stimulus, meanwhile, confuses a necessary condition with a sufficient one, so (D) doesn’t match.

No flaw. (E) establishes a conditional relationship: if double vents and narrow lapels, then fashionably dressed. It then correctly concludes that the presence of both parts of the sufficient condition leads to the necessary condition. The stimulus, meanwhile, confuses a necessary condition with a sufficient one, so (E) doesn’t match.