All you have to do is count the terms.  If there is
1 term, it's a monomial. If there are 2 terms, it's
a binomial. If there are 3 terms, it is a trinomial.
If there are more than 3 terms, it is just called
a "polynomial".

a. , 3 terms, so trinomial. 
b. ,3 terms, so trinomial.  
c. , 2 terms, so binomial. 
d. , 3 terms, so trinomial. 
e. , 1 term, so monomial. 
f. , 3 terms, so trinomial. 
g. , 4 terms, so polynomial.
h. , 2 terms, so binomial. 
i. , 1 term, so monomial. 
j. , 3 terms, so trinomial. 
k. , 4 terms, so polynomial. 
l. , 2 terms, so binomial. 
m. , 1 term, so monomial.
n. , 2 terms, so binomial. 
o. , 3 terms, so trinomial.

Edwin