First lady Michelle Obama said Tuesday that parents can’t be expected to give their children healthy food if they don’t have good options for groceries nearby. Obama, who is leading a nationwide effort to lower childhood obesity rates, spoke at a Chicago Walgreens store that had expanded to include fresh produce and grocery staples. She called it an example for other parts of the city and the country. The first lady announced in July that Wal-Mart Stores Inc., Supervalu Inc., and other retailers plan over the next five years to open or expand 1,500 stores in areas without easy access to fresh fruit, vegetables and other healthy foods. She has said 24 million people, including 6.5 million children, live in such areas nationwide.