Which shows 60^2 − 40^2 being evaluated using the difference of squares method?

(a)60^2-40^2=(3600+1600)(3600-1600) =10,400,000
(b)6^2-40^2=3600-1600=2,000
(c)60^2-40^2=(60-40)^2=20^2=400
(d)60^2-40^2=(60+40)(60-40)=(100)(2 0)=2,000