Explanation:
The aggregate production planning stage is a crucial step in the production planning process, where decisions are made regarding the overall production strategy for a specified period of time. This stage focuses on determining the optimal production rate, workforce levels, and inventory levels to meet the demand forecasted for the planning horizon.

Decision 1: Scheduling of Machines
During the aggregate production planning stage, one of the key decisions is the scheduling of machines. This involves determining the sequence and timing of production activities to optimize machine utilization and minimize downtime. The goal is to ensure that machines are used efficiently and effectively to meet the production targets.

Decision 2: Amount of Labor to be Committed
Another important decision made during the aggregate production planning stage is the determination of the amount of labor to be committed. This decision involves estimating the required workforce levels to meet the production targets. Factors such as labor productivity, overtime, and subcontracting may be considered to ensure that the labor requirements are met.

Decision 3: Rate at Which Production Should Happen
The rate at which production should happen is a critical decision made during the aggregate production planning stage. This decision involves determining the production rate required to meet the forecasted demand. It takes into account factors such as the desired level of customer service, capacity constraints, and inventory levels. The objective is to balance production levels to meet customer demand while minimizing costs and maintaining a reasonable level of inventory.

Decision 4: Inventory to be Carried Forward
The decision regarding the inventory to be carried forward is also made during the aggregate production planning stage. This decision involves determining the optimal level of inventory to be maintained at the end of each planning period. Factors such as carrying costs, stockouts, and lead times are considered to ensure that the inventory levels are sufficient to meet customer demand without incurring excessive costs.

Conclusion:
Among the options provided, the decision that is NOT taken during the aggregate production planning stage is the "Amount of labor to be committed" (Option B). While labor requirements are considered and estimated during this stage, the specific decision regarding the amount of labor to be committed is typically made during the detailed production planning stage, where specific work schedules and assignments are determined.