In feet, how deep is the world's deepest ocean trench?

The world's deepest ocean trench, known as the Mariana Trench, reaches a depth of approximately 36,000 feet. This makes the answer of 35,840 feet the most accurate choice among the options provided.

This depth reflects the extreme conditions found at the bottom of the ocean, including high pressure and low temperatures, which contribute to the unique ecosystem we find in such deep-sea environments. The measurement of the trench's depth is significant in understanding not only marine biology but also geophysical processes and the geological history of the Earth.

As a point of reference, the other depth figures provided in the options do not align with current scientific measurements of known oceanic trenches. The choice of 35,840 feet is the closest and most significantly recognized depth, making it the correct answer.