Answer: mucilaginous sheath
Explanation:
The answer would be kingdom
In broad terms, finches. In specific terms, he observed how over time, the beak sizes and shapes of said finches changed to adapt to the food sources available.
I hope I was able to help. Best of luck.
SELECTIVE BREEDING INVOLVES CHOOSING PARENTS WITH PATICULAR CHARACTERISTICS TO BREED TOGETHER AND PRODUCE OFFSPRING WITH MORE DESIRABLE CHARACTERS . ... CROSS BREEDING INVOLVES TWO DIFFERENT BREEDS FROM THE SAME SPECIES TO CREATE A NEW BREED