Let's say you want to start a fire using a mirror to focus sunlight. What would you do A) use a plane mirror. B) use a convex mirror , with the object to be ignited positioned at the center of curvature of the mirror. C) use a concave mirror, with the object to be ignited positioned at the center of curvature of the mirror. D) use a concave mirror, with the object to be ignited positioned halfway between the mirror and its center of curvature.