Which INMARSAT systems offer High Speed Data at 64/54 kbps?

The correct answer identifies the INMARSAT systems capable of delivering High Speed Data at rates of 64/54 kbps, specifically the B, M4, and Fleet systems.

INMARSAT B provides a reliable and robust connection designed primarily for voice and data services, including its ability to support high-speed data communications. The M4 system enhances this with higher bandwidth capabilities suitable for various maritime applications, allowing users to take advantage of faster data transfer rates. The Fleet system is also tailored for mobile satellite communication in the maritime industry, focusing on delivering consistent data speeds that can easily reach the specified high-speed data requirements.

In contrast, other systems mentioned in the options, such as A and C, do not adequately provide the same level of high-speed data service or are not primarily designed to achieve those data transmission rates as effectively as the specified systems. Hence, the selection of B is based on these systems’ demonstrated capability to meet the high-speed data needs.