Some of the luggage ......... not yet arrived.

The correct answer is A: has.
Let's break down why:
The word "luggage" is a collective noun.
Collective nouns refer to a group of things as a single unit.
Even though "luggage" might consist of many bags, we treat it as one general mass or item.
Because we are treating it as a singular unit, we need a singular verb.
Out of the options, only "has" is a singular verb that agrees with "luggage".
Therefore, the correct sentence is: "Some of the luggage has not yet arrived."
"Have" and "are" are plural verbs, and "is" typically describes a state of being, not an action of arriving in this context.