Why does Sylvia decide not to share the secret of the white heron with the man?

A、Because she realizes that the bird is an integral part of the nature, with which she shares a close bond.;
B、Because she realizes that white heron verges on extinction and it's her responsibility to protect it.;
C、Because the man is too assertive and aggressive to be trusted.;
D、Because the man does not return her affection.