Explanation:
Use the serial comma in this construction and enjoy — if you want to be AP-compliant, this is one of only two opportunities you’ll have.

Using the comma here helps with the clarity of the sentence so the reader understands that CRT modifies both television sets and computer monitors.

The serial comma, AKA the Oxford comma, has been one of the most passionately argued points of punctuation for many years now. We clung to it fiercely at WhatIs for a long time — years after the rest of TechTarget had gone all AP style on it. But business writing has increasingly evolved toward the simplest style possible to convey meaning and maintain readability and, inevitably, we’ve bowed to AP.

Here’s the AP ruling on the serial comma:

IN A SERIES: Use commas to separate elements in a series, but do not put a comma before the conjunction in a simple series: The flag is red, white and blue. He would nominate Tom, Dick or Harry.

Put a comma before the concluding conjunction in a series, however, if an integral element of the series requires a conjunction: I had orange juice, toast, and ham and eggs for breakfast.

Use a comma also before the concluding conjunction in a complex series of phrases: The main points to consider are whether the athletes are skillful enough to compete, whether they have the stamina to endure the training, and whether they have the proper mental attitude.

The AP Stylebook is available online.

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Answer: a. or b., depending on guidelines followed.

Explanation:
A comma before a conjunction is sometimes called the Oxford comma or the serial comma. According to AP style, the Oxford comma should only be used when required for clarity, not in a simple list.

AskOxford explains the derivation of the Oxford comma. They say it’s optional — well, they would, wouldn’t they.

One of the most common arguments in favor of the Oxford comma is that leaving it out can sometimes cause ambiguity but including it will never impair meaning.

If your writing is supposed to follow any standard guideline, check to see what the rule is. Otherwise, whether you use the Oxford comma or not, the important thing is to be consistent.