Two gametes,each carrying a mutant recessive allele for a different gene/enzyme in the adenine biosynthetic pathway,come together to form a diploid embryo.The individual derived from this embryo will display a:

A)lethal phenotype in media lacking adenine supplementation.
B)wild-type phenotype,capable of synthesizing adenine.
C)a weak adenine requirement for survival (intermediate phenotype).
D)a profound defect in adenine synthesis as two enzymes are missing.
E)embryonic lethality.