Answer:
Option D is correct.
Step-by-step explanation:
The monomial function is that algebraic function having only one term in it and it can not consists of negative power.
And even monomial is that have even degree.
Option A:
It has one term but contain negative power
Hence, incorrect.
Option B:
It has one term but of odd degree
Hence, incorrect.
Option C:
It has 2 terms
Hence, incorrect
Option D:
It has only one term and of even degree and hence, correct.
