Question $5$

Select the correct statement$($s$)$ regarding IEEE $802\mathrm{.}11$ WLAN.

a$.802\mathrm{.}11$ standard includes the Distributed Coordination Function $($DCF$),$ and an optional Point Coordination Function $($PCF$)$

b$.$ the Point Coordination Function $($PCF$)$ enables centralized network access

c$.$ the Distributed Coordination Function $($DCF$)$ is a contention$-$based access method

d$.$ all statements are correct