Answer:The correct answer is 3. Zn2+. Zn2+ is a cofactor that assists in enzyme function.
Explanation:A cofactor is a molecule or ion that is required for the proper functioning of an enzyme. It helps the enzyme carry out its catalytic activity.
Among the options provided, the cofactor is Zn2+. Zinc (Zn2+) is a common cofactor that plays a crucial role in enzyme catalysis. It is involved in stabilizing enzyme structures and facilitating chemical reactions.
Let's go through the options to identify the cofactor:
1. NADP+ is a coenzyme involved in redox reactions, but not a cofactor.
2. Insulin is a hormone involved in regulating blood sugar levels, not a cofactor.
3. Zn2+ is a cofactor that participates in various enzymatic reactions.
4. Biotin is a coenzyme that carries carbon dioxide in carboxylation reactions, not a cofactor.
5. Oxytocin is a hormone involved in reproductive functions, not a cofactor.
Therefore, the correct answer is 3. Zn2+. Zn2+ is a cofactor that assists in enzyme function.