A monomial is an expression with a single term. A binomial is an expression with 2 terms.
Looking at the given question,
a. 3y is a single term. Thus, it is a monomial
b. - 9 + h. The expression has two terms. It means that it is a binomial
c. Wr + 5wr is also a binomial
d. -7agh is a monomial
e. 2 is a monomial
f. k + 12 is a binomial
