Answer:
sq. cm.
Explanation:
The lateral area of a cone is given by the formula

Where, r is the radius, and l is the slant height
r is given as 3 cm, but slant height is not given. Let's use the pythagorean theorem on the triangle created by 3cm , 4cm, side and lateral side (slant height).
Let slant height be l:

Now plugging into the formula, we get:
Lateral area =

Second answer choice is right,
sq. cm