Which option is a make$-$or$-$buy decision?

a$.$

This strategy plays one supplier against another and places the burden of meeting the buyer's demands on the suppliers.

b$.$

This strategy is a part of the continuing trend toward using the efficiency that comes with specialisation.

c$.$

The few$-$suppliers strategy implies that, rather than looking for short$-$term attributes such as low cost, a buyer is better off forming a long$-$term relationship with a few dedicated suppliers.

d$.$

In this strategy, manufacturers, restaurants and assemblers of products buy components and subassemblies that go into final products.