Sentence Correction

It is an oversimplified view of cattle raising to say that all one has to do with cattle is leave them alone while they feed themselves, corral them, and to drive them to market when the time is ripe.

(A) all one has to do with cattle is leave them alone while they feed themselves, corral them, and to
(B) all one has to do with cattle is to leave them alone to feed themselves, to corral them, and
(C) all one has to do with cattle is leave them alone while they feed themselves and then corral them and
(D) the only thing that has to be done with cattle is leave them alone while they feed themselves, corral them, and
(E) the only thing that has to be done with cattle is to leave them alone while they feed themselves, to corral them, and

This question has been discussed quite a few times, but I am posting it again because it is still not clear the why the correct answer is: C

Source: 1000 SC

IMO: D