In the Fruitfly Drosophila Melanogaster,red and Yellow Eye Pigments Are

In the fruitfly Drosophila melanogaster,red and yellow eye pigments are synthesized through the pterin pathway.These,plus the brown pigment synthesized through the ommochrome pathway,produce the dark red Drosophila eye color.A part of the pterin pathway (simplified) is shown below.
Consider the genes encoding Enzyme 1 ("e1") ,Enzyme 2 ("e2") and Enzyme 3 ("e3") ,respectively.What are their predicted genetic interactions?

A) e1 is recessively epistatic to e2,and e2 is recessively epistatic to e3.
B) e1 is recessively epistatic to e3,and e3 is recessively epistatic to e2.
C) e3 is recessively epistatic to e1,and e2 is recessively epistatic to e1.
D) e1 is recessively epistatic to e2 and to e3.
E) e2 is recessively epistatic to e1 and to e3.