单选题 .  President Barack Obama's pick to head the Environmental Protection Agency (EPA), Lisa Jackson, has spent 20 years as an environmental officer at the state and national levels. She'll need every bit of that experience to revive an agency that has been corrupted for years, say scientists and environmentalists who welcomed this week's announcement.
    A 16-year veteran of EPA's Superfund site remediation (整治) program before taking the top environmental job for the state of New Jersey, Jackson holds a master's degree in chemical engineering. "She will be an outstanding administrator, committed to defending the integrity of the science on which EPA regulations must be based," says David Michaels, a research professor of environmental and occupational health at George Washington University (GWU) in Washington, D.C.
    That combination of skills and ethics is badly needed at EPA, say Michaels and other scientists. Kathryn Mahaffey, who left EPA this summer for GWU after 15 years of studying the risk to humans from exposure to pollutants, says that she was instructed three years ago by a politician to "go back and recalculate" her results on blood mercury levels among U.S. women. Political interference has grown so serious, she says, that outside scientists "aren't sure what scientific publications coming out of EPA they really should have confidence in."
    One issue waiting for the next EPA administrator is whether the agency will regulate carbon emissions under the Clean Air Act. Although the U.S. Supreme Court told EPA a few years ago to re-examine its opposition to doing so, agency Administrator Stephen Johnson said this summer that "the Clean Air Act is the wrong tool for the job". An assistant to Obama said that Obama would instruct EPA to regulate carbon under the act if Congress didn't adopt a cap-and-trade system in the next 18 months. Another policy opposed by many environmentalists—to deny California and other states the right to tighten auto emission standards—could be reversed by the new EPA administrator.
    As head of New Jersey's EPA, Jackson developed a plan to slash the state's carbon emissions and worked with other Northeast states on a regional program to do the same. Dena Mottola Jaborska, executive director of Environment New Jersey, credits Jackson with making the state "a leader on global warming." At the same time, some groups have criticized Jackson for making inadequate progress on cleaning up toxic waste sites. This month, she became chief of staff to Governor Jon Corzine. If confirmed by the Senate, Jackson, 46, would become the first African-American to lead EPA.1.  During her career, Lisa Jackson had spent the longest time in ______.