In their native habitat, amaryllis plants go dormant when the soil in which they are growing dries out during the dry season.
Conclusion (therefore)
Houseplants should have water withheld during part of the year so that they go dormant.
Evidence (when)
Amaryllis plants in their native habitat go dormant when the soil dries out during the dry season.
Evaluate
This argument uses a causal/comparative reasoning pattern. It notes that in nature, amaryllis thrive by entering a dormant state during the dry season and concludes that replicating this pattern in houseplants will help them thrive. The critical link is the idea that inducing dormancy is beneficial for their thriving—not merely a survival strategy to avoid immediate death from drought. The argument thus assumes that the dormancy itself confers some benefit that contributes to the amaryllis’s overall thriving.
Goal
We need to select an answer that supplies the missing link: the assumption that triggering dormancy (by withholding water) is beneficial for amaryllis plants, and not simply a side effect of unfavorable conditions that merely prevents death. In other words, the argument depends on the view that dormancy has a positive or necessary role in the plant’s ability to thrive.
Too Strong / Irrelevant
(A) mentions that most plants go dormant at some time, but that fact is irrelevant to whether amaryllis benefit from induced dormancy.
Irrelevant
(B) discusses the difficulty of keeping amaryllis as houseplants compared to other plants, which does not impact whether withholding water to induce dormancy is beneficial.