What is the name for the measure of a drug's relative safety for use, computed by the ratio of the lethal dose for 50 percent of the population over the effective dose?

In 1992, hurricane andrew left a wake of destruction through florida. one victim of the storm was a reptile-breeding facility. over 900 burmese pythons were set free, and today thousands of pythons live in florida. these pythons are an invasive species, or a harmful species not native to the region. 1. what impacts do you think the burmese pythons might have on local ecosystems