The correct option is B 3
The zero of any one of the factors will satisfy the equation:
x4−(p−3)x3−(3p−5)x2+(2p−9)x+6=0
Select (x−1)=0, which implies x=1
Using this in f(x)=x4−(p−3)x3−(3p−5)x2+(2p−9)x+6=0
we get f(1)=14−(p−3)13−(3p−5)12+(2p−9)1+6=0
which implies, p=3