Which of the following is MAXIMUM distance for 50 micron multimode fiber at 4Gb?

10 meters is too short; 50 micron multimode fiber can easily exceed this distance at 4Gbps.

For 4 Gigabit Fibre Channel (4GFC) over 50/125 micron OM2 multimode fiber, the industry standard maximum transmission distance is 175 meters. This distance is a specified limit to ensure reliable signal integrity at that speed and fiber type, typically when using Short Wave (SW) SFPs.

800 meters is typically the maximum distance for 1Gbps Fibre Channel over standard multimode fiber, or for higher speeds with optimized laser bandwidth multimode fiber (e.g., OM3 at 10Gbps can reach 300m), making it too long for 4Gbps over standard 50 micron multimode.

2 kilometers is a distance typically achieved with single-mode fiber or very specific long-reach multimode optics at much lower speeds, far exceeding the capability of standard 50 micron multimode at 4Gbps.