If equivalent resistance of identical resistors in series combination is S and in parallel combination is P. If 5 = n P, then find the minimum possible value of n?

For n identical resistors of resistance R:
Series combination: S = nR
Parallel combination: P = R/n
Given 5 = nP, substituting P = R/n:
5 = n (R/n) ⇒ 5 = R, so n = 4.
Answer: (d) 4.