Select the most appropriate option to fill in the blank.
Scientists all over the world are engaged in ______ how to find a vaccine for COVID-19.
Answer & explanation
Correct answer: option 1
The most appropriate option to fill in the blank is:
Option 1: researching
Explanation: The sentence is discussing the activities of scientists related to finding a vaccine for COVID-19. The word "researching" accurately describes the process of conducting systematic study and investigation to gather information and make progress towards a solution.