<span>An observation of the red shift of galaxies suggests that the universe is expanding. The correct option among all the options that are given in the question is the first option or option "a". I hope that this is the answer that you were looking for and it has actually come to your help.</span>
A line that is falling towards the x axis represents an object that is negatively accelerating, or slowing down. When the line hits the x axis, the object has stopped moving. If the graph continues below the x axis, the object has changed direction and is moving backwards at increasing velocity.
From the formula,
v=2πr/T
V(velocity is inversely related to T),so when v increases then time period will decrease.
Option a is correct.
