Which action is the best example of a direct observation

The answer is D Determining the seal population of an island by counting seals in 10 square meters of the island on e2020

Since you didn't have any extra information about the question I'll be presenting an example from my own textbooks that I've used.

An example of a direct observation is listening to a cricket chirp at night, and counting the number of chirps per minute.

Direct Observation is where the evaulator watches the subject in their usual habitat without disrupting or altering it.