Feather color in budgies is determined by two different genes, y and b, one for pigment on the outside and one for the inside of the feather. yybb, yybb, yybb or yybb is green; yybb or yybb is blue; yybb or yybb is yellow; and yybb is white.
a blue budgie is crossed with a white budgie. which of the following results is possible?

a) green offspring only
b) yellow offspring only
c) blue offspring only
d) green and yellow offspring
e) a 9: 3: 3: 1 ratio

Blue offspring only

Explanation:

If A blue budgie is crossed with a white budgie.

i.e yyBB or yyBb × yybb

let use yyBb for blue budgie,so we have; yB, yb, yB, yb representing the columns on the horizontal rows of the punnet square.

on the other hand, in white budgie yybb, we will have yb, yb, yb, yb representing the rows on the vertical column of the punnet square.

if a dihybrid cross occurs among these representative, all progeny in the punnet square will be yyBb, showing that they are all Blue offspring only.

the law of original horizontality explains:   why rocks appear in layers. correct answer: b the law suggests that all rock layers are originally laid down (deposited) horizontally and can later be deformed.   the principle is used by geologists to make assumptions about the relative ages of sedimentary rocks.