The Boolean function F$($A$,$ B$,$ C$,$ D$)=$ A $$ B $$ C $$ D $=1$ means:

a$.$ All inputs are ones $($A $=1,$ B $=1,$ C $=1,$ D $=1)$

$$ b$.$ One or three of the inputs are ones v

c$.$ One or two or three of the inputs are ones

d$.$ All inputs are zeros $($A $=0,$ B $=0,$ C $=0,$ D $=0)$