Answer:
Both A and B
Explanation:
True breed is a breed that is 100% identical with the parent, the traits inherited from that parents are 100% controlled by same allele of a gene hence they are exact copy.
A single gene can have several alleles, it is the allele that combines together that determines what is seen or expressed.
Allele for blue colour is dominant over allele for red color and that is what led to the phenotypic appearance of the offspring which is blue and the red color is masked. Also, because they are true breeds it means the genotype have the same allele e.g. AA