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 the market when the time is ripe.

A.
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

Please answer with explanation.

My doubts are:
- Do so many "and", as in C, make the sentence clumsy or arkward? If not, when to use such "and"?
- What are the differences between "is to leave" and "is leave" in the above sentences? And how to use each case?
Another case: is "is leaving them alone ..." correct?
Many thanks to who can clear my doubts.

[spoiler]OA: later[/spoiler]