Aerial metagenomics specifically refers to the method where DNA samples are collected directly from the air in a particular habitat, hence option 1 is correct.

Option 2 is not the correct answer as it refers to avian genomics (the study of the genetic material of birds), which is a different field of study.

Option 3, though it may involve air-borne devices, it does not involve the collection of genetic material directly from the air. The samples here are vehicle-based, not environment-based.

Option 4, involves the use of drones which could be airborne but the samples collected are from land and water surfaces, not directly from the air.

In essence, the key to understanding aerial metagenomics is that it involves the collection of genetic material directly from the atmosphere of a given habitat.