I am pretty sure the answer is C.
Taking into account the rule of three for the change of units, the mass of the book is 45600 miligrams.
First of all, the rule of three is a mathematical tool that helps you quickly solve proportionality problems.
Having three known values and one unknown, a proportional relationship is established between all of them in order to find the fourth term of the proportion.
If the relationship between the magnitudes is direct (when one magnitude increases, so does the other; or when one magnitude decreases, so does the other), the rule of three is applied as follows, where a, b and c are known values and x is the unknown to calculate:
a → b
c → x
So: 
Being 1 kg equivalent to 1000000 milligrams, In this case the rule of three is applied as follows: if 1 kg equals 1000000 milligrams, 4.56×10⁻² kg equals how many milligrams?
1 kg → 1000000 milligrams
4.56×10⁻² kg → x
So:

<u><em>x=45600 miligrams</em></u>
In summary, the mass of the book is 45600 miligrams.
Learn more:
Answer is 4,400,000 kg • m/s
Answer: Convention
Explanation: Convention is pretty well known for being a process that transmits heat from one place to another place with the movements of heated particles. I got this answer from my notebook during my chemistry class.
Hope this answer helps!
Answer:
It will take 2.45 seconds.
Explanation:
A football field measured 120 yards, that is arround 0.068 miles, the car is moving with a constant speed so the formula we have to apply for this is:


in order to obtain the time in seconds:
