Answer:
The expression that belongs in the box is 8 x 4
Option C is correct answer.
Step-by-step explanation:
We need to find Which expression belongs in the box?

The property applied here is associative property of multiplication.
Associative property of multiplication states that:

So, if we apply the property to our question we have:
a = 3
b = 8
c = 4
So, the expression will become: 
So, the expression that belongs in the box is 8 x 4
Option C is correct answer.
Answer:
A prospective study
Step-by-step explanation:
A prospective study watches for outcomes, such as the development of a disease (in this case cancer). It also usually involves taking a group of subjects and watching them over a long period of time. The outcome of interest should be common between them (whether certain smoking habits lead to the development of cancer in British doctors).
Answer:
≈0.819232 or 
Step-by-step explanation:
times 

Answer:
to what?
Step-by-step explanation: