According to the base pairing rules, in RNA adenine pairs with uracil (A-U) in RNA, and cytosine pairs with guanine (C-G).
a) It is known that the most common codon is AUG. The start codon is the first codon of mRNA, that's why it contains U. So, a complementary DNA code must be TAC, so it will be transcribed into AUG:
3'TAAACTGTACAGGGCCATAACT5'
b) Starting from the start codon AUG and according to the base pairing rules, mRNA will be transcribed into the following sequence:
DNA: 3'TAAACTGTACAGGGCCATAACT5'
RNA: AUGUCCCGGUAUUGA
c) According to the genetic code chart, the following mRNA sequences will code for the following amino acid sequences:
RNA: AUG UCC CGG UAU UGA
Protein: Met-Ser-Arg-Tyr-
The last codon (UGA) is a stop codon, so it will not be translated. It is a signal for translation termination.