Which shows 42^2 − 38^2 being evaluated using the difference of perfect squares method?

a) 42^2 − 38^2 = (1,764 − 1,444)(1,764 + 1,444) = 1,026,560
b) 42^2 − 38^2 = 84 − 76 = 8
c) 42^2 − 38^2 = (42 − 38)^2 = (4)^2 = 16
d) 42^2 − 38^2 = (42 + 38)(42 − 38) = (80)(4) = 320