The length of ST is 10 units, the length of S't" is 2 units.
This means the dilated figure was decreased by a factor of 5.
Because it is smaller it would be a scale factor of 1/5 ( 0.2 as a decimal).
Answer:
and 
Step-by-step explanation:
Options

Required
Select the unit rates
Unit rate involve two items where the first item being measured can be any positive number, but the second item must be measured in units (i.e. 1)
For clarity:
If
represents unit rate, then 
Having said that:
Only
and
satisfy the condition of unit rates; others are not because they have a denominator other than 1
Be more specific on the first one
First and last terms of the given equation are perfect squares. They can be written as
(4p^2)^2+ 2.(4p^2).5+(5)^2
It's like identity 1: (a+b)^2=a^2+2ab+b^2
So a=4p^2 and b=5
Therefore it is equal to (4p^2+5)^2