Find the Value of the Laplacian $\nabla ^ { 2 } f \text {of } f ( x , y ) = x y ^ { 3 }$

Multiple Choice

Find the value of the Laplacian $\nabla ^ { 2 } f \text {of } f ( x , y ) = x y ^ { 3 }$ at the point $( 1,1 )$

A) $0$
B) $\frac { 11 } { 4 }$

C) $2$
D) $3$
E) $4$
F) $5$
G) $6$
H) 9