Answer:
D. The number of cattle ranchers decreased in the past five years
Step-by-step explanation:
According to Jennifer M Schieltz and Daniel I Rubenstein (2016), "More than a quarter of earth's land surface is used for grazing domestic livestock." This has negative effects on availability of pasture for herbivorous wildlife such as the deer.
Increase in the number of cattle ranchers decreases the availability of pasture and vice versa.
Hence, the decrease in the number of cattle ranchers over the past five years led to an increase in the deer population due to a decrease in competition for pasture.