In this Eg there is a clear difference in usage of that and it :
In the seventeenth century, the French astronomer Jean Picard became the first person to accurately measure the length of a degree of a meridian and used that to calculate the size of Earth.
A. the French astronomer Jean Picard became the first person to accurately measure the length of a degree of a meridian and used that to calculate the size of Earth.
B. the French astronomer Jean Picard became the first person to accurately measure the length of a degree of a meridian and made use of it in the calculation of the size of Earth.
C. the French astronomer Jean Picard made the first accurate measurement of the length of a degree of a meridian and used it to calculate the size of Earth.
D. the first accurate measurement of the length of a degree of a meridian was made by the French astronomer Jean Picard, and he used that to calculate the size of Earth.
E. the length of a degree of a meridian was first accurately measured by the French astronomer Jean Picard, who calculated the size of Earth with it.
Can anyone explain why c is correct and not b
GMATNinja