the answer is definitely A.
I'd have to say that the list of choices doesn't go far enough.
Advances in Astronomy have been occurring for at least the past two millennia (2000 years). Maybe longer.
A piece of blue paper appears blue because the paper absorbs all colors of light except blue. <em> (b)</em>
So any light that bounces off of the paper and enters your eye must be blue light !
Answer: This is what I found hope it helps
Explanation:
My guess for this one would be; 400 N
My reasoning would be; it starts at 0 on both X and Y, if you need to get to 1.00 meters thats 4/4. 1/4 of 1.00 is .25, and on .25 its on 100 so multiply it by 4 to make 1.00 and you get 400 N