When deleting a node from a binary search tree that has two children, the reason we can replace its element with the greatest value in its left subtree is because:
a. The value will be greater than everything on its left, and since it was in the left subtree, it will be less than everything in the right subtree
b. The value will become greater or equal to the values of its children
c. Greatest value is the easiest to move
d. We don't replace nodes when removing from a bst