The Co-op the Grange is comparable to a
a monopoly
b
Native American Tribes
c
Big Business
d
a Labor Union

a labor union

Explanation:

Grange Cooperative Supply Association usually called Grange Coop is a cooperative society offers that provides petroleum products, garden supplies, agricultural supplies, consumer goods, farm products, pet supplies, etc to farmers.

The Co-op the Grange is comparable to a labor union. A labor union seeks out for the best interest of the workers and that's exactly what the Co-op the Grange does.