Task: Question Answering
Input (English): Background Paragraph: The quantity of small plastic fragments floating in the north-east Pacific Ocean increased a hundredfold between 1972 and 2012.Marine pollution is a generic term for the harmful entry into the ocean of chemicals or particles. The main culprits are those using the rivers for disposing of their waste. The rivers then empty into the ocean, often also bringing chemicals used as fertilizers in agriculture. The excess of oxygen-depleting chemicals in the water leads to hypoxia and the creation of a dead zone.Marine debris, also known as marine litter, is human-created waste that has ended up floating in a lake, sea, ocean, or waterway. Oceanic debris tends to accumulate at the center of gyres and coastlines, frequently washing aground where it is known as beach litter.In addition, the Pacific Ocean has served as the crash site of satellites, including Mars 96, Fobos-Grunt, and Upper Atmosphere Research Satellite. 
Story: Robert and his brother Jeff are both farmers whose farms are near large rivers. These rivers eventually flow into the Pacific Ocean. Robert recently switched to a different brand of fertilizer to increase the yield on his crops.  This fertilizer contains a chemical that tends to destroy oxygen when it comes into contact with it. Due to heavy rains on his farm, large amounts of this fertilizer have been leaking into the river near Robert's farm. Meanwhile, Jeff uses fertilizer that is very stable and does not leak into the rivers near his farm. 
Question: Who will contribute less to the formation of dead zones in the Pacific Ocean?
Output (English): Jeff.