The correct answer is: Close relationship with suppliers; Minimal set up time and costs; Uniform loading of all stages of the production process.

A close relationship with suppliers (so that raw materials are delivered as they are required), minimal set-up time and costs (so that small production runs are feasible) and uniform loading of all stages of the production process (so that the speed of all processes matches the rate at which the final product is demanded by customers) are key requirements of successfull JIT.

It does not matter whether raw materials are perishable or not (but if they are perishable, JIT is even more desirable.)