Answered

One main purpose of a colon is to 

Aintroduce a list.B. mark the boundaries between strong words.C. replace a question mark.D. show emphasis.

Verified Answer :

AIntroduce a list.

It also has other purposes and if you're interested in learning more, there are plenty of resources on the web.

One purpose of a colon is to A) Introduce a list. For example is, I went for shopping today. And here are the things I bought: Sugar, sneakers and jeans.