Monomials and polynomials
A monomial is an expression with only have multiplications , dont have sum or rest.
So therefore A,B and C are monomials ( observation : option B have a - sign, but its not resting, its multiplication by (-1))
Then, only remaining option is D, 5m + 2u
Answer is OPTION D,
becausd 5m + 2u is a binomial