If a, b, c, d, e are five consecutive odd numbers, their average is

Answer: Option D

Clearly,
b = a + 2
c = a + 4
d = a + 6
e = a + 8
∴ Average
$$\begin{array}{rl}& =\frac{a+\left(a+2\right)+\left(a+4\right)+\left(a+6\right)+\left(a+8\right)}{5}\\ & =\left(\frac{5a+20}{5}\right)\\ & =\left(a+4\right)\end{array}$$