The correct option is A in Pennsylvania
An adjunct is a word, phrase or clause that can be eliminated from the
sentence, without affecting it grammatically. The sentence would still
make sense without an adjunct. Adjuncts are usually adverbs, adverb
phrases or adverb clauses. When the adverb phrase, "in Pennsylvania" is removed, the sentence is still grammatically correct. Hence it's the adjunct and option D is correct. "Sent" is the verb and "my application" is the direct object. Without any of these, the sentence ceases to be a sentence; hence options A and B are incorrect. "To a university" is the indirect object, without which the sentence sounds strange; hence it isn't an adjunct and option C is incorrect.