Why can humans not rely on the transport method used in small organisms

This is because human have a much larger surface area. Small organisms have a small surface area and thus simple diffusion meets their transport requirements. As the size of the organisms increases, its surface area to volume ratio decreases. This means it would take days for molecules to diffuse through a large animal, so humans have a circulatory system with a pump to transport materials quickly around their bodies. Therefore due to their large size, humans require a specialized transport system.

the correct answer is a. adverse selection problem

Explanation:

Adverse selection is when sellers have information that purchasers do not have, or vice versa, about some aspect of product quality. It is thus the tendency of those in dangerous jobs or high-risk lifestyles to purchase life or disability insurance where chances are greater they will collect on it.