A cone has radius 3 and height 4. Your classmate calculates its surface area as shown:
S. A.=π(5)2+π(3)2=25π+9π=3π. Explain your classmate's error.

A. The lateral area should have been calculated as π(3)(4).
B. The lateral area should have been calculated as π(3)(5).
C. The lateral area should have been calculated as π(4)(5).
D. The base area should have been calculated as π(1.5)2.