In the partners and suppliers dimension, ITIL Version 5 explains several factors that influence an organization's supplier strategy. One of the explicitly listed reasons is subject matter expertise: an organization may decide that it is less risky to use a supplier that already has expertise in a required area rather than trying to develop and maintain that expertise in house. This directly supports option D, obtaining capabilities that are difficult to develop internally. ITIL also notes other factors such as strategic focus, resource scarcity, cost concerns, risk concerns, external constraints, and fluctuating demand patterns. None of these suggest eliminating oversight or internal management; in fact, ITIL emphasizes that supplier relationships still require governance, agreements, and coordination. Option A may apply in some insourcing cases, but it is not the best reason to engage external suppliers. Option B is the opposite of supplier engagement. Option C is clearly wrong because using suppliers does not remove governance responsibilities. Therefore, based on the partners and suppliers dimension, D is the correct verified answer.