Fact 1: Viruses are not cells.

Fact 2: Plant cells are surrounded by a cell membrane and a cell wall.

Given the two facts above, answer the question "What lacks walls and membranes?" with the following options: 
- deserts
 - flower cells
 - viruses
 - fungi
 - tree cells
 - bacteria
 - plant cells
 - alpacas


 

   viruses      