Final answer:
The Spanish could help American Indians adapt to new livestock through fencing techniques, education on European farming methods, and establishing communal grazing areas, while prohibiting livestock would not be helpful.
Step-by-step explanation:
The Spanish could have assisted American Indians in adapting to the new species of livestock in several ways. Option (a), introducing fencing techniques to American Indian farmers, would be practical as it could help limit the damage done by livestock to crops and aid in the management of animals. Option (b), providing education on European farming methods, would allow for the transfer of knowledge and skills necessary for the care and breeding of livestock. Option (c), establishing communal grazing areas for livestock, would fit the Native American concept of shared land resources, while also organizing the use of land for grazing in a manner that might prevent overuse and disputes. Option (d) is not viable, as prohibiting the introduction of European livestock wouldn't assist in adaptation but rather hinder the potential benefits they could bring.