Answer:
A, B and C (but see below).
Step-by-step explanation:
C.
(7 + 12i - (7 - 14i)
= 7 - 7 + 12i + 14i
= 26i.
Looks like you have typos in part B so I've rewritten it:
B.
(4 + 6i)(3 + 21i
=12 + 8i + 18i + 12i^2
= 12 + 8i + 18i - 12
= 26i
Also I think A is:
.13i+ 3i + 5i+ 5i
= 16i + 10i
= 26i.
