Which of the following is punctuated correctly?
1) I need to know whether you are able to perform the following functions of the job, revising existing marketing materials, promoting the company at trade shows, and reaching potential customers through direct mail campaigns.
2) I need to know whether you are able to perform the following functions of the job; revising existing marketing materials, promoting the company at trade shows, and reaching potential customers through direct mail campaigns.
3) I need to know whether you are able to perform the following functions of the job: revising existing marketing materials, promoting the company at trade shows, and reaching potential customers through direct mail campaigns.

3) I need to know whether you are able to perform the following functions of the job: revising existing marketing materials, promoting the company at trade shows, and reaching potential customers through direct mail campaigns.

Explanation:

It has the colon at the right place, and the commas observe the standard Oxford Comma convention for making a list. Both colon and comma are punctuation marks that can be used in making a list. Usually, the colon is put after stating "the following," while commas separate one item from the other and are used when the items are three or more, with the last item started with a comma.