Final answer:
HR is most likely to perform strategic planning at the corporate level using an upstream/downstream model.
Step-by-step explanation:
HR is most likely to perform strategic planning at the corporate level using an upstream/downstream model. Strategic planning involves setting long-term goals and objectives for the organization and developing strategies to achieve them. This activity is performed at the corporate level as it requires a holistic view of the organization and its external environment.
For example, HR may analyze the current workforce and future talent needs to align with the organization's strategic goals. They may also develop initiatives to attract and retain top talent and ensure that the compensation and benefits programs are aligned with the organization's strategy.