Which of the following aspects is a defining characteristic of living organisms?

$A$ ball of snow when rolled over snow increases in mass,volume and size. Is this comparable to growth as seen in living organisms? Why?

Which of the following pairs represents the defining features of living organisms?

Biologists focus on which aspect to identify a living organism?

$S$ Statement: Reproduction leads to an increase in the number of organisms.
$R$ Reason: In reproduction,organisms produce new individuals similar to themselves upon reaching maturity.
$(a)$ Both $S$ and $R$ are true,and $R$ is the correct explanation of $S$.
$(b)$ Both $S$ and $R$ are true,but $R$ is not the correct explanation of $S$.
$(c)$ $S$ is true and $R$ is false.
$(d)$ $S$ is false and $R$ is true.

Living organisms show self-consciousness. Explain.