Step 1: Understanding the bad taste in monarch butterflies.
Monarch butterflies acquire their bad taste during the larval stage when they feed on milkweed plants, which contain toxic compounds. These compounds make them distasteful to predators.
Step 2: Analyzing the options.
(A) while pupating: Incorrect — The bad taste is developed during the larval stage, not during pupation.
(B) in adult stage: Incorrect — The bad taste is not developed in the adult stage.
(C) during egg laying: Incorrect — The bad taste is not associated with egg laying.
(D) in larval stage: Correct — Monarch larvae feed on toxic milkweed, which gives them their bad taste.
Step 3: Conclusion.
The correct answer is (D) in larval stage, as the monarch butterfly acquires its bad taste during the larval stage.