Digital SAT Reading and Writing Practice Question #1671

While researching astronomer Henrietta Swan Leavitt, a student took the following notes: - In 1908, Henrietta Swan Leavitt published a study of Cepheid variable stars in the Small Magellanic Cloud. - She observed that brighter Cepheid stars exhibited longer periods of pulsation. - This period-luminosity relationship allowed astronomers to calculate the true intrinsic brightness of distant stars. - By comparing intrinsic brightness to apparent brightness, astronomers could accurately measure cosmic distances across the universe. - Edwin Hubble later used Leavitt's period-luminosity law to prove the existence of galaxies outside the Milky Way. The student wants to emphasize Leavitt's specific contribution to measuring cosmic distances. Which choice most effectively uses the relevant information from the notes to accomplish this goal?