Right answer is (c) 35
The explanation is: Clearly (2n + 1) is an odd number. Therefore this is a case of binomial with an odd power.
For a binomial expansion with odd power, there are two middle terms.
Case 1: \(\frac{n+1}{2}\) = 19
Therefore n = 37
Case 2: \(\frac{n+3}{2}\) = 19
Therefore n = 35