Read the sentence.

students who purchase parking spots are able to park in the lot closest to the entrance.
( who purchase parking spots is underlined )
the underlined part of the sentence is a

a. restrictive phrase.
b. nonrestrictive phrase.
c. restrictive clause.
d. nonrestrictive clause.

The underlined part of the sentence " who purchase parking spots is underlined" is a restrictive clause. Option c is correct.

A restrictive clause is an adjective clause adding essential information to a sentence.  "who purchase parking spots" is an essential part of the sentence, consequently, the clause is a restrictive clause.

This type of clause limits or identifys the nouns it modifies and cannot be removed from a sentence without changing the sentence’s meaning.

no its not a run on sentence however i think you meant wet suits not sours also a run on sentence would be like surfers surf all winter long in southern california by using wet sours to keep them warm and the live their all year long  

lol

today at the bank, an old lady asked me to check her balance. so i pushed her over.