Explain how the surface area and volume of cell affect the rate of exchange of materials in and out of cells in multicellular organisms

An organism must has a large surface area to volume ratio in order to exchange material easier 

in animals erythrocytes have a flat concave shape that allows them to carry more haemoglobin and also increases its surface area to volume ration so that the length and availability of a surface is less for the materials to travel 

multi cellular organisms tend to have flat and elongated respiratory surfaces to allow for a higher surface area to volume ratio in order to increase the rate of gas exchange 

the ilium in most mammals is flat and elongated and is covered with microvilli to increase surface area and to reduce the cells volume therefore reducing its surface area to volume ratio 
hope that helps

Ithink the answer is d.