complex- before the car wash is an adverb clause
The correct answer is c) past.
Past (preposition) - from one side to the other of something, or in front of something.
Rephrased: He passed his grandmother's house on his way to school.
Passed - from the verb <em>to pass</em>, past tense, coudln't be used in this sentence.
Passet is not a word.
Pasted - past form of the verb <em>to paste, </em>does not fit in the context.