Choose the most suitable option for blank (60):
A verb is used to express an occurrence, action, or state. It is the grammatical center of the predicate in a sentence.
An auxiliary verb is a verb which gives is used in the formation of tenses, moods, tones, etc.
Option C is correct as the subject (suitcases) is plural and the sentence talks about a fact.
The other options are wrong as no other tense can be used here.
The correct answer is C) arrive.