The value of n for the first term will be 1 and greater ...
So its the third choice
To find the lateral area of a cone, use this formula:

where r is the radius (in this case, 11) and h is the height (in this case, 26)
Try plugging the values in. If you need additional help, feel free to ask!
The principal is $25 and the rate is 4%.
So after t years: A(t) = 25(1.04)^t