What type of vessel requires a marine radio for communication with bridges with respect to passenger limits?

The requirement for a marine radio for communication with bridges specifically pertains to all passenger vessels of 100 gross tons or greater. This regulation is in place to ensure safety and effective communication in busy waterways, especially where large passenger vessels are navigating nearby bridges, which often have specific height and clearance restrictions.

These larger vessels, due to their size and the number of passengers they carry, are more likely to encounter regulated waterways that necessitate coordination with bridge operators. Effective communication helps to avoid accidents and facilitates the safe passage of vessels under bridges.

The other choices do not qualify in the same way. Vessels without passengers, fishing vessels under 30 feet, and those not carrying any cargo do not fall under the same operational protocols that apply to large passenger vessels, which are subject to more stringent safety and communication regulations.