In a Solar Cell,placing Semiconductors of the P-Type and N-Type

In a solar cell,placing semiconductors of the p-type and n-type in contact with each other via a conducting wire accomplishes these two things:

A) It ensures that the current flows in a specific direction as it facilitates the conduction of electricity.
B) It ensures that only certain energies of solar radiation cause electricity to flow as it facilitates the conduction of electricity.
C) It ensures that only certain energies of solar radiation cause electricity to flow as it facilitates the flow of electricity in either direction.
D) It ensures that only oxidation takes place as it facilitates the conduction of electricity.