Translation and Regulation - Medical Science

Q1:

What is the maximum number of different amino acids in a polypeptide chain coded by the synthetic polyribonucleotides (UCAG)5?

A One

B Two

C Three

D Four

ANS:C - Three

Isn't it 4, amino acids that can coded by (UCAG) 5?

UCA GUC AGU CAG.

Anyone, please clarify this.