The answer would be C.
-1 has more than one output.
hope this is correct,, have a nice day :))
The sum would be written as:

It goes from n=1 to =5 because it is the first 5 terms of the sum.
The sequence has a first term, a₁, of 1. The common difference, d, is 3. The explicit formula would then be:

Using the distributive property to simplify, we would have: