During inhalation, the diaphragm becomes .....and ribs move ......
The correct options are
B.flat
C.downwards
During inhalation, the diaphragm flattens and the ribs move upwards and outwards due to contraction of the intercostal muscles. This increases the volume of the thoracic cavity and the pressure decreases. As the outside pressure is higher, air gushes into the lungs.