Two students, Student 1 and Student 2, did the same experiment simultaneously to measure parallax. Student 2's eyes are farther apart than Student 1's eyes. The steps of the experiment are listed below.
1. Hold the thumb out at arm's length.
2. Look at the thumb and alternately open and close each eye.
3. Estimate the distance by which the thumb appears to move with respect to background objects.
Based on the experiment, what would the students most likely conclude about the parallax method of measurement of star distances?
a. both the parallax measurements should be taken at the same time
b. parallax shift remains the same when measured by different instruments
c. the shift in parallax while measuring star distances depends on the distance between the two points of observation
d. parallax would be most effective in measuring distances to stars which are more than a billion light years away from Earth
