Explanation: VHF-DSC (Digital Selective Calling) employs Frequency Shift Keying (FSK) to transmit digital messages reliably over marine radio frequencies. International standards, particularly ITU-R Recommendation M.493, precisely define the modulation characteristics for this system. The standard signaling rate, or **baud rate**, for VHF-DSC is **1200 baud**. This ensures universal compatibility among all DSC-equipped marine radios. The system uses a frequency shift of ±400 Hz from a 1700 Hz center frequency (i.e., mark at 1300 Hz, space at 2100 Hz). The associated **index of modulation** is specified as **2.0 +/- 10%**. Options A, C, and D are incorrect because their listed baud rates (800, 1500, and 1800 baud) do not conform to the established international standard for VHF-DSC communication. Therefore, 1200 baud and a modulation index of 2.0 are the correct parameters.