What will come in place of blank space (_) in the following series.
_ o n p m _ n p m o _ p m o n _

Given: _ o n p m _ n p m o _ p m o n _

Now, we check each options.

Option (a): o n p m (Not Follow)

o o n p / m n n p / m o p p / m o n m

Option (b): p n o m (Not Follow)​

p o n p / m n n p / m o o p / m o n m

Option (c): n m p o (Not Follow)​

n o n p / m m n p / m o p p / m o n o

Option (d): m o n p (Follow)​

m o n p / m o n p / m o n p / m o n p

The pattern will follow: m o n p

Thus, correct option is (d).