The principle encourages us to resolve a set of stimuli, such as trees across a ridgeline, into smoothly flowing patterns A.) depth perception.
B.) perception.
C.) similarity.
D.) continuity.

Your answer is c. explanation: plasma  is the fourth state of matter, derived from the gaseous state of matter.  plasma  can contain free  electrons  and/or  ions. while  plasma is never neutral, it can either be positively or negatively charged.  gases, however, are electrically neutral.