The parents of a 15-year-old Michigan boy who allegedly opened fire in a high school this week pleaded not guilty on Saturday to involuntary manslaughter charges. Jennifer Crumbley, 49, and James Crumbley, 45, appeared at the virtual Oakland County hearing after being apprehended by law enforcement at a vacant building in Detroit late Friday. Prosecutors say the pair are culpable because they stored the firearm their son is accused of using at Oxford High School in an unlocked drawer in their bedroom, and because they didn’t alert authorities of the possibility he had the weapon on the day of the shooting. Karen McDonald, the county prosecutor, told the court that evidence showed the parents bought the gun for Ethan Crumbley, pointing to social media posts from Jennifer Crumbley in which she told followers she took Ethan to a shooting range with a weapon that was his Christmas present. “It’s clear …