Which word in the sentence is a subject complement?

terry was the first person in line for the carnival ride.

a.
first

b.
ride

c.
person

d.
line

The correct answer is option A, first

The complement of subject can be an adjective, noun and pronoun that follows a linking verb. Linking verb can be  : is , am , are, was, were, has been , is/are being, might have been etc.

Here in this sentence the linking verb is was which is predecessor to the word “first person” and thus “first” can be stated as complement of a subject.  

the answer is c) abandoned properties that are contaminated with hazardous materials.