Final answer:
Conceptual skill is the most important essential managerial skill for top level managers, as it involves strategic thinking and decision-making.
Step-by-step explanation:
The most important essential managerial skill for top level managers, according to Katz, is conceptual skill. Conceptual skill refers to the ability to think strategically, analyze complex situations, and understand the organization as a whole. It involves seeing the big picture and making decisions that align with the organization's goals and objectives.
For example, a top level manager of a multinational company needs to have conceptual skill to evaluate market trends, identify growth opportunities, and develop long-term strategic plans for the company's success.
While technical, efficient performance, and human skills are also important, conceptual skill sets top level managers apart as they are responsible for setting the overall direction and vision of the organization.