A student reads a list of several measurements.
1. the amount of dust given off by exploding stars.
2. the rate at which galaxies are moving away from Earth.
3. the rate at which the light emitted by a star switches between red and blue wavelengths.
4. the amount of hydrogen present in stars.
Which measurements are used as evidence of the age of the universe?
A. 1 and 2
B. 2 and 3
C. 1, 2 and 3
D. 1, 2, and 4
