Pick up the incorrect statement from the following :

$($a$)$ A rich mix of concrete possesses higher strength than a lean mix of desired workability with excessive quantity of water.

$($b$)$ The strength of concrete decreases as the water cement ratio increased.

$($c$)$ If the water cement ratio is less than $0\mathrm{.}45$ the concrete is not workable and caused honeycombed structure.

$($d$)$ Good compaction by mechanical vibration, increases the strength of concrete.