I would say B : main sequence is the answer . this is the answer i believe because the star will increase in size and than shine brightly and when it's done , it will get smaller turning into nebula , eventually exploding sometime around the last stage , but not the last stage of b , c, or d
i really hope that this helps you a lot.
Answer: yes
Explanation: because its artificial piece specifically designed to help that certain area
1. After the collision, their velocities have switched. This is Newton's third law of motion.
2. The total momentum is conserved.
3. The same thing would happen if the collision is totally elastic.
For 4 and 5.
Using the conservation of momentum equation
m1v1 + m2v2 = m1'v1' + m2'v2'<span />