Answer: b.

Explanation:
The official pronunciation of RFID is R-F-I-D – saying the letters of the initialism separately. However, if something can be said in two syllables rather than four, that’s usually going to happen (and who am I to argue, since I pronounce ASAP as A-sap). RFID is commonly pronounced ARE-fid. Whether you pronounce the letters separately, though, or say are-fid, “an” is the correct article because both sound as if they start with a vowel.

There are also those who pronounce RFID as RIFF-id or RIFF-dee. If that’s how you pronounce it, you could write a RFID but be aware that most people would read that as “a ARE-EFF-EYE-DEE“ or “a ARE-fid,” which would not leave a good impression of your intelligence. Try saying them out loud and you’ll see what I mean.

The Urban Dictionary discusses RFID, including its pronunciation.

***

Follow me on Twitter @tao_of_grammar

Answer: a.

Explanation: To conform to AP style, abbreviate state names when used in conjunction with a town or city name. (However, if the city is not specified, spell out the full state name.)

David Davies published this handy AP style tipsheet.

Here’s a list of abbreviations for state and province names, including both current and old-style.