Solve the Problem $x ^ { 2 } + y ^ { 2 } = 4$

Multiple Choice

Solve the problem.
-Find the mass of a thin circular plate bounded by $x ^ { 2 } + y ^ { 2 } = 4$ if $\delta ( x , y ) = x ^ { 2 } + y ^ { 2 }$ .

A) $8 \pi$
B) $2 \pi$
C) $1 \pi$
D) $4 \pi$