The correct answer is B) preparing to make the shore power connection. A hand-held portable phase sequence indicator would be used in this situation to verify the phase sequence of the shore power connection before making the connection. This is necessary to ensure the phases are properly aligned, which is critical for safely connecting to shore power and preventing damage to the vessel's electrical system. The other answer choices are incorrect because they do not relate to the specific situation of verifying phase sequence prior to a shore power connection. Installing a new synchroscope, replacing a defective solenoid, or paralleling alternators would not require the use of a portable phase sequence indicator in this context.