60 elements! I don't exactly know every element known, so if you are asking that, please tell us, but what I do know is that there were 60 elements in the periodic table by 1860.
Answer:
1. D. Boat B will cause a change in the position and speed of boat A.
2. B. A collision
3. D.
4. Most likely C
Explanation:
Strong and good for you bro