Read the passage carefully and answer the following question:

Self Induction. When a current I flows through a coil, flux linked with it is φ = LI, where L is a constant known as self inductance of the coil.

Any charge in current sets up an induced emf in the coil. Thus, self inductance of a coil is the induced emf set up in it when the current passing through it changes at the unit rate. It is a measure of the opposition to the growth or the decay of current flowing through the coil. Also, value of self inductance depends on the number of turns in the solenoid, its area of cross-section and the permeability of its core material.

Question:

The inductance L of a solenoid depends upon its radius R as