Final answer:
Trust building is the necessary relationship skill during the initiating activity of building a strategic alliance.
Step-by-step explanation:
The relationship skill that is necessary during the initiating activity of building a strategic alliance is Trust building. Trust is a crucial factor in any partnership or alliance as it establishes a foundation of reliability and mutual understanding between the parties involved. Trust-building involves open communication, transparency, and the willingness to collaborate and share information. By establishing trust, partners can work together effectively and achieve their shared goals.