The correct option is B (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)
(a) There are 12 pairs of ribs. Each rib is a thin flat bone connected dorsally to the vertebral column and ventrally to the sternum. The last two pairs (11th and 12th) of ribs are not connected ventrally and are therefore, called floating ribs.
(b) & (c) Scapula is a large triangular flat bone situated in the dorsal part of the thorax between the second and the seventh ribs. The dorsal, flat, triangular body of scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion. The clavicle (collar bone) articulates with this.
(d) Below the acromion process is a depression called the glenoid cavity which articulates with the head of the humerus to form the shoulder joint.