PEAS... one of the classical Mendelian crosses. Yellow and Smooth are dominant characteristics. The recessive alleles are green and wrinkled respectively. Both yellow and smooth are fully dominant and segregate independently of each other. In the flies, you will be crossing scarlet eyed flies with brown eyed flies. I will not say anything more about the cross here other than to mention that scarlet and brown are not alleles of each other and they segregate independently of each other.