A lab observation notes that a course practical includes silkworm, citrus butterfly, parasites, and molluscs in one economic importance section. The observation points to:

Correct Answer: A

invertebrates can be useful, harmful, or both

Invertebrates have mixed economic roles. Some provide products like silk or food, some damage crops or livestock, and some transmit diseases or serve as parasites. This MCQ belongs to the Economic importance topic in Animal Diversity-I and is written to test concept understanding rather than memorized wording.