I believe it is number 3.
Hope this helps!
I believe the answer is b.
The factors that determines the rate of diffusion in the biological system include: temperature, size of the particles, diffusion distance and concentration gradients. Of all these factors, the most important one is the TEMPERATURE.
The relationship between temperature and the rate of diffusion is a direct one, that is, the higher the temperature the higher the rate of diffusion and vice versa. At high temperature the molecules in the particles move faster because they have higher amount of energy.
The large majority of spiral galaxies are flat, rotating disks. Within the disk, there are stars, dust, and gas. The disk also contains spiral arms and a central concentration of stars known as the bulge of the galaxy.
