Which sentence contains an essential adjective clause ?
a. the sponsor who pays for our uniforms deserves advertising at each game
b. our sponsors, who fund the team, are invited to the opening game
c. after explaining the sponsorship levels, they agreed to join at the silver level
d. during halftime, the speaker announced the sponsors .

B. Our sponsors, who fund the team, are invited to the opening game

The correct answer is A. The sponsor who pays for our uniforms deserves advertising at each game

Explanation:

An adjective clause refers to a clause that mainly describes the noun in a sentence by using two or more words. Additionally, an essential clause is a type of adjective clause that cannot be omitted from a sentence as this would make the sentence incomplete in terms of grammar and sense. Also, essential adjective clauses can be identified as they are not separated from the main sentence by using commas which also means they cannot be omitted as they contain key information for the sentence. Considering this, the sentence that contains an essential adjective clause is "The sponsor who pays for our uniforms deserves advertising at each game" because in this sentence the adjective clause "who pays for our uniforms" is not separated by commas as in other options and this information cannot be omitted as the reader will not understand why the sponsor deserves advertising.