D. 1/4
Explanation:
a perfect square is written in the form
(1)
In our problem, we have this perfect square:
(2)
with C being unknown. However, by comparing (1) and (2), we know that

So, we find

and therefore, the missing term must be

so the complete square is

The correct answer is 19 :)
I don’t know I’m just doing this for the points I’m sorry ☮️✌️
Answer:
This experiment has three factors (shampoo type, gender, whether hair is dyed)
Step-by-step explanation:
the researcher is trying to make a comparison between an old shampoo and a new on and also was gender sensitive as she considers their hair coloration too because it affects the result slightly.
100x=100 if we are solving for x the answer would be one because 100 divided by 100 is one hope this helped