Question

1. scientists are the people that do the investigations and make the discoveries that you read or hear about.

Explanation:

The sentence is about defining what scientists do, and the appropriate word to fill in the blank is "Research" (as "Research scientists" are those who conduct investigations and make discoveries). The context here relates to the work of scientists in the realm of natural science (since research in science, including biology, chemistry, physics etc., involves investigations and discoveries), and the blank requires a word that describes the type of scientists. "Research" fits as it modifies "scientists" to indicate those who perform research (investigations) and make discoveries.

Answer:

Research