Comprehensive and Detailed In-Depth Explanation:

Line Leaders are pivotal in change management, as per the APMG Change Management Foundation, due to their proximity to frontline staff. Option C ("They can support and influence local staff") is correct because their role enables them to provide direct support, address concerns, and model change behaviors, influencing their teams effectively. Option A overstates their authority, Option B is false as they are affected by change, and Option D is unrealistic given their operational duties. Their effectiveness lies in their local influence and support capacity.