Portfolio rebalancing involves periodically adjusting the portfolio's asset class weights back to their original policy targets, as specified in the strategic asset allocation. This process, known as drift correction, ensures that the portfolio's risk-return profile remains aligned with the investor's long-term objectives. Tactical asset allocation (Option B) involves deliberate deviations from policy weights for short-term gains, while generating alpha (Option A) refers to active strategies aimed at outperforming benchmarks. The correct answer is C, as rebalancing focuses on restoring systematic risk exposures to their intended levels.