Vertical integration occurs when an organization expands into earlier or later stages of its value chain, such as acquiring suppliers or distributors. A major disadvantage is reduced flexibility to change partners. Once the organization owns or controls a supply or distribution stage, it may be locked into specific technologies, capacity levels, cost structures, or operational relationships. Option B is less convincing because vertical integration often reduces supplier or buyer bargaining power. Option C is not generally true because integration may support differentiation through quality or supply control. Option D is also incorrect because vertical integration may increase control over proprietary knowledge. Internal audit should assess integration risks, including fixed-cost exposure, reduced flexibility, and operational complexity. Therefore, Option A is correct.