Answer: OPTION D.
Step-by-step explanation:
You have the expressions given in the problem:

To find the product of both expression you must multiplicate them.
You must multiply the numerators of both expression and the denominators of both expression.
Keeping the above on mind, you obtain that the product is:


Answer/Step-by-step explanation:
Line segment AB consists of segment AC and segment CB.
AC = 7 cm
CB = 21 cm
The entire segment, AB = 21 + 7 = 28cm
The ratio of the segments partitions can be stated as follows:
Ratio of AC to CB = AC:CB = 7:21 = 1:3 = 
AC is ¼ of AB 
CB is ¾ of AB 
C temp. pH and regulatory molecules