In April 2011, Dan is audited by the IRS for the year 2009. During the course of the audit, the agent discovers that Dan%u2019s deductions for business travel and entertainment are unsubstantiated, and a $6,000 deficiency assessment is proposed for the tax year 2009. The agent also examined some prior-year returns. The agent discovers that Dan failed to report $40,000 of gross business income on his 2007 return. Gross income of $60,000 was reported in 2007. The agent also discovers that Dan failed to file a tax return in 2002. Will the statute of limitations prevent the IRS from issuing a deficiency assessment for 2009, 2007, or 2002? Explain.