Answer
$B∪C= \{ 2,4,$ or $ x|x$ is an odd integer \} $
Work Step by Step
$B = \{x|x$ is an odd integer $\} $
$B= \{1,3,5,7,9,11,13,...... \}$
$C = \{ 2,3,4,5\}$
$B∪C$ is set of numbers in B or in C or in both B and C
$B∪C= \{2,4,1,3,5,7,9,...... \}$
$B∪C= \{ 2,4,$ or $ x|x$ is an odd integer \} $