Key Concept: Skeletal deformities in fish fry often trace back to a vitamin needed for collagen production.
Why it's correct: Vitamin C is essential for collagen synthesis and bone development; its deficiency causes skeletal deformities like Lordosis (spinal curvature) in fry.
Why others fail: Vitamin A relates to vision, Vitamin D to bone mineralization (not curvature specifically), and Vitamin E to fertility and antioxidant defense — none is directly tied to collagen-driven spinal deformity.