Read about the biotechnology R&D work profile described and fill in the blank robin works in a laboratory at a large research hospital. The she studies are too tiny to see with a microscope

The __specimens___ she studies are too tiny to see with a microscope

Explanation:

Specimen include microorganisms, cells, large molecules, biopsy samples, metals, and crystals.  Research and Development (R&D) are carried out in order to gather information and generate practical knowledge using both theoretical and experimental means. Most of these microorganisms and cells are too small to be seen with the naked eye, so scientists use microscopes to study them.  Biotechnology research and development have proved very helpful in modern time.  It has enabled the refining of industrial processes and the discovery and production of biological enzymes.

answer; preoperational(d)