Which of the following prevents nutrient-rich topsoil from being eroded by wind and rain? bacteria, plant roots, stones, or fences

The answer is plants root

Plants get their daily nutrition from the soil and they use their roots in order to get it.

the plants' root will grow to the nutrient rich area of the soil and make it's composition stronger , making it harder to be blown away by the wind

Nothing will delay it, but drinking some lemon (squeeze 3) would cut it, making it last a few days, but its not good to do that. won't hurt you but the next month will be more cramps.. take some advils with you on the trip