Answer:
(d) Mexico has rigid social classes
Explanation:
The correct answer is the letter "D". Commas are used in different types of occasions and situations. The sentence is stating a fact and that is why it doesn't need a comma; the message needs to be read clear. In letter "a", "b" and "c" the comma is used in a wrong way. Because it separates what it doesn't need to be separated; or it just simply stops the "flow" of the sentence.
