All you need is the definition of conditional probability:
[tex]P(A\mid B)=\dfrac{P(A\cap B)}{P(B)}[/tex]
So
[tex]P(C\mid D)=\dfrac{P(C\cap D)}{P(D)}\iff0.26=\dfrac{P(C\cap D)}{0.22}\implies P(C\cap D)=0.0572[/tex]
[tex]P(D\mid C)=\dfrac{P(C\cap D)}{P(C)}\iff0.17=\dfrac{0.0572}{P(C)}\implies P(C)\approx0.34[/tex]
and the answer would be B.
