The students who __________ a top grade in pharmacology were admitted to postgraduate studies.

The sentence can be completed with the word "achieved." The full sentence would read: "The students who achieved a top grade in pharmacology were admitted to postgraduate studies."

Explanation

In this context, "achieved" refers to the students attaining or successfully reaching a high grade in their pharmacology course. The use of the term emphasizes the effort and accomplishment that led to their eligibility for postgraduate studies. Achieving a top grade is often a critical criterion for academic progression, particularly in competitive fields such as pharmacology. It suggests that the students not only understood the material but excelled, indicating their preparedness for advanced studies. This recognition can be vital for their future careers in academia or the pharmaceutical industry.