What is the primary form of evidence that has led astronomers to conclude that the expansion of the universe is accelerating?

a) observations of the speeds of individual galaxies in clusters
b) measurements of the rotation curve for the universe
c) measurements of how galaxy speeds away from the milky way have increased during the past century
d) observations of white dwarf supernovae

The primary form of evidence that has led astronomers to conclude that the expansion of the universe is accelerating is by the observation of white dwarf supernovae.

D

Explanation

The Universe is becoming larger in an accelerated rate which means the galaxies are stretching away from the observer with increasing acceleration.

The speed with which the galaxies in the universe are receding away from the observer is varying with time.

This process is termed as accelerating expansion of universe.

In 1998, 2 independent teams first observed this. The first evidence for accelerating expansion of universe was obtained by observing the red shift of white dwarf supernovae named Ia supernovae.  

d.7.5cm is your answer