I’m not entirely sure. So I’m sorry if it’s wrong but I think this is the correct answer:
T-C-G-A-C-C-T-G-A
(Becsuse every letter will be the opposite of its match. So I’m the sequence when it says A, you would replace it with T (because A goes with T) , and when it says G you would replace it with C (because G always goes with C)