Answer:
GTACTA
Step-by-step explanation:
All you need to do is switch the nitrogenous bases presented in the first strand with their nitrogenous base pairs. Aka:
C = G
A = T
T = A
G = C
A = T
T = A
So, Strand 1 is CATGAT and Strand 2 (the answer) is GTACTA
Hope this helps you, love :3