What should come in place of the question mark (?) in the given series?
215, ?, 221, 223, 227, 229

Given: 215, ?, 221, 223, 227, 229

Logic: Numbers are increasing + 2 and + 4 alternately.

215 + 2 = 217

217 + 4 = 221

221 + 2 = 223

223 + 4 = 227

227 + 2 = 229

So, the missing term is 217.

Thus, correct option is (d).