If B = {1, 3, 5, 7, 9}, the set-builder representation of B is
B = {x: x is an odd natural number less than 10}
Option B is wrong as the set of odd numbers less than 10 gives {-∞,- - - - -, -5, -3, -1, 1, 3, 5, 7, 9}
So, B is a set of all odd natural numbers less than 10.
=> Option D is correct