Changes in sea level
are not only a result of changes in water temperature, affecting water density, but of melting glaciers as well. (A) are not only a result of changes in water temperature, affecting water density, but of melting glaciers as well - parallelism issue - Not only X , but also Y is correct idiom
(B) not only result from changes in water temperature, which affect water density, but also when glaciers melt - parallelism issue - Not only result ... , but also when
(C) are a result not only of changes in water temperature, which affect water density, but also the melting glaciers - parallelism issue
(D) result not only from changes in water temperature, which affect water density, but also from the melting of glaciers - Correct
(E) result from not only changes in water temperature, affecting water density, but as well as when glaciers melt - parallelism issue - Not only X , but also Y is correct idiom
Answer D