This graph shows the dose-response curve for a lethal dose of a particular toxin: Dose response curve related to mortality for a particular toxin. Doses up to 1,000 mg per kg result in death for 0 percent of those exposed to the toxin; a dose of 2,000 mg per kg results in death for 6 percent of those exposed to the toxin; a dose of 5,000 mg per kg results in death for 20 percent of those exposed to the toxin; a dose of 10,000 mg per kg results in death for 50 percent of those exposed to the toxin; and a dose of 20,000 mg per kg results in death for 100 percent of those exposed to the toxin.

According to the graph, approximately how much larger is the LD50 dose for this toxin than the threshold level?

3,000 mg/kg
8,000 mg/kg
9,000 mg/kg
10,000 mg/kg