If triangle ABC is dilated by a factor of 1/2 to produce triangle A'B'C', what is the length of A'C' (a'c') after the dilation? What is the measure of angle B' (m∠b')?
a) a'c' = 15, m∠b' = 31°
b) a'c' = 17, m∠b' = 28°
c) a'c' = 60, m∠b' = 62°
d) a'c' = 15, m∠b' = 62°