Choose the correct option $:-$
$(a)$ The first seven pairs of ribs are called true ribs.
$(b)$ The sternum is a large triangular bone situated at the ventral part of the thorax.
$(c)$ The scapula has a slightly elevated ridge called the spine which projects as a flat, expanded process called the acromion.
$(d)$ Below the acromion is a depression called the glenoid cavity which articulates with the head of the humerus.

• A
  Only $a, b$ and $c$
• B
  Only $a, c$ and $d$
• C
  Only $b, c$ and $d$
• D
  Only $a$ and $c$