The correct response is diversified farming. All of the other answer choices involving degrading the landscape, whereas diversified farming restores the landscape's nutrients by cycling the nutrients of the land in a proportional manner, rather than exhausting a specific nutrient/resource by exercising intensive farming.

The correct response is subsistence agriculture. The definition of subsistence agriculture is planting enough for just your family. We don't  that what she is doing is sustainable - she could be dumping chemicals and destroying biodiversity for all we know. The key is that we know that she is planting just enough food for her family.

The correct response is monoculture farming. Mono = one. Gary only plants 1 crop at a time so his farm is a monoculture. If he planted more than one crop at a time, then you could call his farm a polyculture (poly = many) or diversified farming. If he was interested in managing his farm for biodiversity, then you could say he is engaging in agroecology farming. 

A plant almost never uses as much fertilizer as it is given, and in the case of synthetic fertilizers especially, the nutrients are also often over-applied for efficiency's sake. This over-application leads to fertilizer buildup in the soil as more and more goes unused. When certain concentrations of the fertilizers are reached, the chemicals in the fertilizer form salts, leading to what we call soil salinization, which is a condition where plants can't grow very well.

While tilling aerates the soil, which makes planting easier, it does so at the cost of killing many soil organisms and disturbing the soil microbiome, leading to soil microorganism death as well. Tilling also increases soil erodibility so wind and other disturbances are more likely to erode away the topsoil.

A very large collection of the same species, such as a large field of one type of crop only, is extremely attractive to species-specific pests, which only see a great deal of food. This means monoculture farmers need to use a lot of pesticide. Such collections are also very vulnerable to disease; because all of the plants in a field are identical, this means a single fungus or virus can infect them all very easily. Finally, every plant needs the same kind of nutrient, which means they use up what's in the soil very quickly. This means monoculture farmers also need to use lots of fertilizer.

During the 1930s and 40s, "miracle" rice and dwarf wheat varieties were developed by Norman Borlaug in the countries named. The rest of the innovations listed came later.

Seed-tree cutting best fits this definition because most trees in this harvest method are cleared, but a few mature trees are left uncut so as to provide seeds for future stands to grow. 

Clear-cutting is when an entire stand is cut for harvest. Single-tree cutting is harvesting select mature trees. Shelterwood cutting is when the forest is "thinned" of more mature trees, and a group-selected cut is when a small patch of trees is selected and cut.

Clear-cutting puts the hardwood ecosystem at risk of soil erosion and depletes the resource, while single-tree cutting would reap little profit and dense stands could limit growth of shade-intolerant saplings. Seed-tree leaves too few slow-growing oaks to disperse seeds and group-selection cutting is not optimal for a tree whose saplings grow right where the acorns drop from the tree. 

Shelterwood cutting thins out the forest, allowing younger, sun-loving trees to grow. This method is often preferred for slow-growing hardwoods and limits soil erosion while maximizing yield.

The main concern with fire supression is the overcrowding of fire-adapted tree stands, which can be problematic for wildlife attempting to forage or migrate. A buildup of high-density wood fuel is also a high risk for a catastropic wildfire and is not befitting of a healthy ecological community. However, overgrowth of stands does not inherently pose a risk for soil erosion, as root systems from dense tree stands will likely hold the soil in place.