Hint: Bucket handle movement is one the most important movement of ribs of our body that result in change in the transverse diameter of the thorax. This movement helps in the change of dimensions of the thorax while expiration and inspiration as during inspiration more volume is required in the thorax so that air can enter.
During the process of inspiration, the diameter of the thoracic cavity increases by ribs swinging outwards causing elevation of the sternum and the ribs which increase the volume of the thorax so that inhaled air can enter the thoracic cavity. This movement of ribs is performed by the help of the external intercostals muscles. The ribs which elevate during the process of inspiration are 6th rib to 10th rib and the movement of these ribs is similar to the handles of a bucket. Therefore, this movement of ribs is called bucket handle movement. These ribs move around two axis and result in the lowering of the anterior and middle part of the rib. The movement that helps ribs to elevate occurs at costovertebral joints.
Hence, The correct answer is option (C).
Note: During the process of inspiration, the anterior end of the ribs is lower than the posterior end of ribs and the difference between them is around 4 cm. The middle part of the ribs position also changes and moves lower than anterior and posterior ends. This movement increases the volume and transverse diameter of thorax so that the required amount of inhaled air during the process of inspiration enters the cavity easily. This movement is called bucket handle movement of ribs.