Final answer:
Decreasing the cell membrane's surface area will not speed up glucose diffusion into a cell; in fact, it would slow down the diffusion process by limiting the space available for molecules to pass through.
Step-by-step explanation:
The option that will NOT speed up the net rate of diffusion for glucose into a cell is c. Decreasing the surface area of the cell membrane. Increasing the surface area is known to increase the rate of diffusion, because it provides more space for molecules to pass through the membrane. Conversely, decreasing the surface area would reduce the rate at which molecules like glucose can enter the cell, thus slowing down diffusion.
Several factors influence the rate of diffusion, including the concentration gradient, temperature, and permeability of the cell membrane. A higher concentration gradient (a), a higher temperature (b), and increased membrane permeability (d) would all contribute to a faster rate of diffusion. However, the notion that greater distance speeds up diffusion is incorrect, as an increased distance would actually slow it down.