Frogs use positive pressure breathing mechanism for ventilation by

Explanation

Frogs utilize a positive pressure breathing mechanism, which is different from the negative pressure mechanism seen in mammals. They create higher pressure in their buccal cavity (mouth) by closing their nostrils and elevating the floor of the mouth to push air into the lungs. This method is effective for their aquatic and terrestrial habitats. Options A and D are incorrect because frogs lack the rib and diaphragm structures needed for those breathing processes. Option C is incorrect because while nostrils are involved in the breathing process, the pressure change occurs in the mouth, not the nostrils.