On the September equinox, the equator experiences approximately 12 hours of daylight. The equinox occurs when the Sun is directly above the equator, resulting in equal amounts of daylight and darkness throughout the day. This happens twice a year, in September and in March.

Option 1 states that the equator experiences 8 hours of daylight. This is incorrect as the equator typically experiences more daylight during the equinox.

Option 2 states that the equator experiences 9 hours of daylight. Similarly, this is incorrect as it underestimates the amount of daylight during the equinox.

Option 3 states that the equator experiences 10 hours of daylight. Again, this is incorrect as it also underestimates the actual amount of daylight during the equinox.

Therefore, the correct answer is option 4, which states that the equator experiences 12 hours of daylight on the September equinox. This means that on this particular day, the equator has an equal amount of daylight and darkness.