If biologists study small things that can't normally be seen with an unaided eye, then what do biologists study?

Answer choices:
- Bio-thermodynamic studies
 - Small things with a microscope
 - smallest agents of disease
 - basic building blocks of life
 - genetic material
 - The study of biolife in space
 - DNA damage and mutations
 - The study of bio

 

  Small things with a microscope        