Arkin Comp. is a nongovernmental, not$-$for$-$profit organization involved in research. Arkin's expenses classification in the notes to the financial statements should classify which of the following as support services?

A$.$ Salaries of staff researchers involved in research.

B$.$ Salaries of fundraisers for funds used in research.

C$.$ Costs of equipment involved in research.

D$.$ Costs of laboratory supplies used in research.