The first was an old TV repair shop called B's TVs-a shack, mostly, where the tenant sat inside smoking cigars, waiting for customers to trigger the front door's buzzing optical alarm like flies in a bug zapper.

It illustrates that the optical door alarm is annoying.

It suggests that the tenant doesn't want customers.

It shows that the tenant takes advantage of people.

It conveys the idea that the TV repair shop is uninviting.

In this paragraph:

The first was an old TV repair shop called B's TVs-a shack, mostly, where the tenant sat inside smoking cigars, waiting for customers to trigger the front door's buzzing optical alarm like flies in a bug zapper.

The author

Conveys the idea that the TV repair shop is uninviting.

Explanation:

To understand this answer we need to analyze it carefully. First of all, with "a" option. The author never mentions something annoying. That is a perspective claim, however, in our paragraph, we have only descriptions. B option talks about the tenant not wanting customers. However, the most logical idea would be to keep the store closed. So it is incorrect. C option talks about the tenant taking advantage of people, however, the description includes no abusive scene. Nevertheless, we do found the scene very polluted. Which guides us to an idea of a very disturbing environment.

It illustrates that the optical door alarm is annoying.

The simile that compares the customers setting off the alarm to flies in a bug zapper. The purpose of the simile is to show that the alarm is annoying. The main focus of the sentence is that the man is waiting to hear the alarm. While the alarm signals a customer, the customer is not the focus of the tenant's effort. Describing the alarm sound as that of a bug zapper indicates that the alarm is annoying.