Answer:
Option A
Explanation:
Clearly, we observe the following partern : The first letters follow the pattern +3 i.e.
$B + 3 \rightarrow E, E + 3 \rightarrow H, H + 3 \rightarrow K$
The second letters follow the pattern +2 i.e. $M + 2 \rightarrow O, O + 2 \rightarrow Q, Q + 2 \rightarrow S$
The third letters follow the pattern + 2 i.e. $O + 2 \rightarrow Q, Q + 2 \rightarrow S, S + 2 \rightarrow U$
Thus, the missing term is KSU. Hence, the answer is (a).