D and F Block Elements

Given below are two statement: one is labelled as Assertion $\mathbf{A}$ and the other is labelled as Reason $\mathbf{R}$ Assertion A: $5 \mathrm{f}$ electrons can participate in bonding to a far greater extent than $4 \mathrm{f}$ electrons Reason R: $5 \mathrm{f}$ orbitals are not as buried as $4 \mathrm{f}$ orbitals In the light of the above statements, choose the correct answer from the options given below