Answer: e. Both b & d
Step-by-step explanation:
Economies and Efficiency can be achieved by managing costs better. This can be done by training employees more so that they may use deep skills gained to be able to keep costs low by being more efficient on the job.
A good place to reduce costs would be the common costs. The business can target these costs by optimising them which means to reduce costs while still maximizing output and value. Reducing the costs here would lead to better efficiency.