Today's managers understand that the success of any effort at improving quality and productivity must include .

d. employees

Explanation:

As we know that the success of an organization would depend upon the performance of the employees and the quality than the company provides to its clients and the customers

Also at the same time the manager understand this that the success is based on the effort done by the employees in terms of productivity and the quality

Therefore as per the given options, the option d is correct

ANd, the rest of the options are incorrect

answer; rapid growth in buyer demand and high buyer switching cost;

answer; read and consider the content of the items;