Select all of the following true statements: A large boundary layer results in increased heat conductance between the leaf and the surrounding air. A smoke machine might be used on a cold, clear night with air temperatures hovering around 2 C to prevent freezing. It is impossible for a plant leaf to be damaged by frost if the air temperature is at least 2 C. Radiation frost and advection frost are mutually exclusive; they do not happen simultaneously. Sprinkler irrigation might be used on a cold, clear night with air temperatures hovering around -2 C to prevent freezing. A wind machine might be used on a cold, clear night with air temperatures hovering around 2 C to prevent freezing. On a cold, clear night, with air temperatures hovering around 2 C, a plant leaf is more likely to freeze if the wind is blowing