Final answer:
c) Adding denitrifying bacteria to the soil is the most likely process to help reduce nitrate pollution. Hence, c) is correct.
Step-by-step explanation:
The most likely process to help reduce nitrate pollution is adding denitrifying bacteria to the soil. Denitrification by bacteria converts nitrates (NO3) to nitrogen gas (N₂), which helps break down the accumulated nitrates in groundwater.
By introducing denitrifying bacteria to the soil, the bacteria can convert the nitrates into nitrogen gas, preventing the nitrates from contaminating the groundwater and potentially causing nitrate pollution in oceans.