It seems that you forgot the answer choices, but lucky for you, I know the answer..
Answer: creating skin tissue by combining cells from different cell lines
A is correct is the answer
Found a similar question with the following choices:
a. living things and flowing water
b. climate and soil properties
c. physical setting and biological community
d. climate and landscape features
In a watershed system, the two main parts are the A. LIVING THINGS AND FLOWING WATER
