Chief joseph vows that he “will fight no more forever” for all of the following reasons except —
a.
he has been advised by his chiefs to surrender
b.
the chiefs have been killed
c.
his people lack blankets and food
d.
he feels sick and sad with loss

The best and only answer to your question is   a. he has been advised by his chiefs to surrender  

Chief Joseph vows that he “will fight no more forever” because all of the following reasons:

the chiefs have been killed
his people lack blankets and food
he feels sick and sad with loss

Hope my answer would be a great help for you.  

Its the land ownerss :)