These would be the elements in row 2 the alkaline metals. Elements in a row usually share many qualities such as electon reactivity as well as similar characteristics like the fact that many alkaline metals are considered Cations, ions with positive charges. Some examples are beryllium and calcium.
Properly identifying each species.
Accurately recording his findings.
Not interfering with ecosystem while studying the birds.
Answer:
they burn no fuel and release no greenhouse gases
Explanation: