Final answer:
Pantothenic acid (B5) does not directly participate in collagen synthesis. This vitamin is crucial for metabolic functions, neurotransmitter synthesis, and cholesterol production. Option (a) is the correct answer.
Step-by-step explanation:
The function that is not a role of pantothenic acid (B5) is collagen synthesis. Pantothenic acid is an essential nutrient and a component of coenzyme A, which is critical for numerous biochemical pathways in the body. Notably, it is involved in the metabolism of glucose, fats, and proteins, and is vital for processes such as the citric acid cycle and fatty acid oxidation. It also assists in neurotransmitter and cholesterol synthesis.
Collagen synthesis, while a vital physiological function, is not directly linked to pantothenic acid but rather involves vitamin C and other factors. Hence, the correct answer to the question is 'Collagen synthesis' (option a).