Final answer:
As surface area-to-volume ratio increases in the agar block diffusion experiment, the diffusion rate also increases, which leads to a decrease in the time required for substances to reach the center of the block.
Step-by-step explanation:
In the agar block diffusion experiment, the surface area-to-volume ratio, diffusion rate, and time for substances to reach the center are closely related. As the surface area-to-volume ratio increases, there is more surface area available for diffusion per unit of volume. This typically results in a higher diffusion rate because there is more membrane through which substances can pass. A higher diffusion rate, in turn, means that substances can reach the center of the cell or agar block faster, decreasing the time required. In summary, the correct relationship is that as surface area-to-volume ratio increases, the diffusion rate increases, and the time for substances to reach the center decreases. This aligns with answer option B: As surface area-to-volume ratio increases, diffusion rate increases, and time to the center decreases.