Factor the Polynomial Completely $y ^ { 2 } + 40 y + 400$

Multiple Choice

Factor the polynomial completely. If the polynomial cannot be factored, write "prime."
- $y ^ { 2 } + 40 y + 400$

A) $( y - 20 ) ^ { 2 }$
B) $( y + 20 ) ( y - 20 )$
C) prime
D) $( \mathrm { y } + 20 ) ^ { 2 }$