Assertion (A): Faces for attacking excavation and construction of tunnels are opened by constructing pilot tunnels.Reasoning (R): Pilot tunnels are suitable at locations when horizontal approach to the centre line of tunnel is shorter than deep vertical shafts.

• A. Both (A) and (R) are true but (R) is the correct explanation of A
• B. (A) is true and (R) is false
• C. (A) is false and (R) is true
• D. Both (A) and (R) are false