A variable in C is$...$

$($a$)$

$...$a symbolic name for a group of bits and an associated data type that tells a compiler how to interpret those bits.

$($b$)$

$...$a symbolic name for a group of bits.

$($c$)$

$...$a calculation involving values, numbers, and operators.

$($d$)$

$...$a specific command that the computer executes when the program is run.