P(A′)=1−P(A)
This is the complement rule.
(A)→(III)
P(ϕ)=0
ϕ is the empty set (no outcome), so the probability is always 0.
(B)→(IV)
P(A∣B)=P(B)P(A∩B); P(B)=0
In P(A∣B), the event after the bar (here B) goes in the denominator.
(C)→(II)
P(B∣A)=P(A)P(A∩B); P(A)=0
In P(B∣A), the event after the bar (here A) goes in the denominator.
(D)→(I)
(A)→(III),(B)→(IV),(C)→(II),(D)→(I)