Unicellular organisms transport essential nutrients directly to all parts of their bodies by the process of diffusion because, they have

Answer Details

Unicellular organisms are single-celled organisms, meaning that their entire body is in direct contact with the external environment. Because of their small size, they have a large surface area to volume ratio, which allows for efficient diffusion of essential nutrients directly to all parts of their body. This means that nutrients can simply move through the cell membrane by the process of diffusion without the need for a specialized circulatory system. Therefore, the correct answer is: "a large surface area to volume ratio".