b. measuring the pulsations of the Sun from stations around the world.
Explanation:
The Global Oscillation Network Group (GONG) is a community-based program that wants to conduct a detailed study of the internal structure of the sun by using helioseismology. GONG relies on a team of six observatories around the world to perform its work. One of the duties of GONG is to measure the pulsations of the Sun from six stations located all over the world.
