Im guessing it's (a) since the numbers go in chronological order and you read the periodic table left to right
Hi
The answer to this question is B. Reaction
In the process of peppering the question with those forty (40 !) un-necessary quotation marks, you neglected to actually show us the illustration. So we have no information to describe the adjacent positions, and we're not able to come up with any answer to the question.
Answer:
F = 2 * 30 / 5 = 12 N to stop forward motion
F = 2 * 40 / 5 = 16 N to accelerate to 90 degrees
(12^2 + 16^2)^1.2 = 20 N average force applied
The answer is C. in sort of a way. You can't technically see black matter. However, it is holding the galaxies together.