Answer: b

Explanation: Use fewer to refer to anything that’s countable. Reserve less to refer to things that aren’t countable. Beans vs. bean dip. (Is it lunchtime?)

So, you would say fewer messages but less spam.

Get it? If so, please pass this on to your local news media. Because they don’t seem to and if they carry on they may yet drive me totally around the bend.
~

Here’s Grammar Girl’s take on mass nouns and count nouns:

A count noun is just something you can count. I’m looking at my desk and I see books, pens, and M&M’s. I can count all those things, so they are count nouns and the right word to use is fewer. I should eat fewer M&M’s.

Mass nouns are just things that you can’t count individually. Again, on my desk I see tape and clutter. These things can’t be counted individually, so the right word to use is less. If I had less clutter, my desk would be cleaner. Another clue is that you don’t make mass nouns plural: I would never say I have clutters on my desk or that I need more tapes to hold my book covers together.

Follow us on Twitter @tao_of_grammar

Answer: b

Explanation:
If something can be expressed as a number, like beans in a jar, always use number. Use amount to refer to things that aren’t quantified, such as bean dip.