Final answer:
According to COLREGs, as the stand-on vessel in a crossing situation with risk of collision, one should initially maintain course and speed but be prepared to take avoiding action if the give-way vessel does not.
Step-by-step explanation:
When you are in charge of a stand-on vessel in a crossing situation and you believe that a risk of collision exists with another vessel 1.5 miles to port, the appropriate course of action is to: C. take avoiding action only after providing the give-way vessel time to take action, and determining that her action is not appropriate. This is according to the International Regulations for Preventing Collisions at Sea (COLREGs). The stand-on vessel should maintain course and speed to allow the give-way vessel to take action. However, if it becomes clear that the give-way vessel is not taking appropriate action, or risk of collision still exists, then the stand-on vessel must take avoiding action to prevent a collision.