Horizontal complexity is a specific term explaining the number of departments in organizations. There is a positive relation between the number of units/departments and horizontal complexity. It is possible to expect emergence of departments after organizations reach a certain size. But, horizontal complexity is not necessarily linked with organizational size; smaller organizations may have more units than the larger ones or large organizations can survive with a simple structure. There might be various factors determining level of horizontal complexity. Organizational purpose, environmental complexity and design approach of top management team are some of these factors. The correct answer is Choice A.