The population of a bacteria colony is measured at $3$:$00,3$:$15,$ and $3$:$30.$ The corresponding population values are $40,80,$ and $160.$ Explain why this does or does not have a linear correlation.

a$.$ This has a linear form because the population doubles every $15$ minutes.

b$.$ This has a linear form because the points form a line when plotted on a graph.

c$.$ This does not have a linear form because the population does not increase by the same amount every $15$ minutes.

d$.$ This does not have a linear form because there are three points.