Select the letter of the term that identifies the function of the clause

in parentheses in the following sentence:
Accurate identification of evidence is necessary (so that charges can be
filed against people suspected of capturing or killing endangered
animals).
a. adjective clause
b. adverb clause
c. noun clause

b. adverb clause

The function of the clause in parentheses in the given sentence is to provide a purpose or a result. Therefore, the correct answer is b. adverb clause.