INLAND ONLY Vessels "A" and "B" are meeting on a river as shown in illustration D029RR below and will pass 1/4 mile apart. Which statement is TRUE?

Correct Answer: Option C — If a passing agreement is reached by radiotelephone whistle signals are optional.

33 CFR 83.34(h) provides that when a passing agreement is reached via radiotelephone, the requirement to sound whistle signals is waived. This rule simplifies communication in congested inland waters, provided both vessels have confirmed the passing arrangement clearly over the VHF radio.