What factor is responsible for the increase in the rate of physical adsorption?

Option B - increase in pressure.
The extent of adsorption is directly proportional to the pressure. Therefore, increase in pressure will cause increase in rate of adsorption.

Keep in mind that temperature also has a role to play in the rate of adsorption. At low temperature, the extent of adsorption increases rapidly with pressure.

Increase in pressure

because as pressure increase volume decrease and concentration increase which shift reaction in forward direction according to le chetlier principle