Answer:
the answer is D
Explanation:
Mass extinctions were first identified by the obvious traces they left in the fossil record. ... Such dramatic changes in adjacent rock layers make it clear that mass extinctions were geologically rapid and suggest that they were caused by catastrophic events (e.g., a period of intense volcanic activity).
Answer:
I hope this a little bit.
A constant velocity means the acceleration is zero.
Object B is positively charged, Object C is negatively charged, Object D is negatively charged.
Answer:
(i)
, (ii)
, (iii) 
Explanation:
(i)
and
represent the points where particle has a velocity of zero and spring reach maximum deformation, Given the absence of non-conservative force and by the Principle of Energy Conservation, the position where particle is at maximum speed is average of both extreme positions:

(ii) Maximum accelerations is reached at
and
.

(iii) Greatest net forces exerted on the particle are reached at
and
.
