Option 1 -> Planning involves setting goals, forecasting, and determining courses of action, which requires extensive mental analysis and decision-making.
Option 2 -> Organizing focuses on arranging resources, assigning duties, and establishing structure to implement plans.
Option 3 -> Controlling involves monitoring performance, comparing results with standards, and taking corrective action.
Option 4 -> Directing deals with leading, motivating, and guiding employees to achieve organizational objectives.
Hence, Option 1: Planning -> Planning is called the "thinking function" because it is a mental exercise that involves analyzing the current situation, forecasting future conditions, setting objectives, and deciding the best course of action before any physical work begins. It requires intellectual work and foresight. -> correct