Select the letter that identifies the type of noun that is in

parentheses in the following sentence:
Most high schools in the (United States) offer both interscholastic and
intramural athletic activities.
a. proper
b. concrete
c. collective
d. abstract
e. possessive form

a. proper

The type of noun in parentheses in the sentence is a. proper. "United States" is a specific name of a country and should be capitalized, making it a proper noun.