What kind of mirror - concave,convex,or plain - would be best suited for use in a solar cooker? Why?

(A) solar cooker uses the heat of sunlight to cook and heat food. $A$ mirror is used to reflect and focus sunlight at a single point. $A$ concave mirror is best suited for this purpose. The concave mirror converges all the incident parallel rays of sunlight at its focus. This concentration of light energy significantly increases the temperature at that point,which is used to cook or heat the food placed there.