How many ribs are present in human beings?

The human rib cage has 12 pairs of ribs (24 ribs).

It is a thin flat bone that is connected to the vertebral column (dorsally) and to the sternum (ventrally). 

True ribs- First, 1-7 pairs of ribs are known as true ribs. True ribs are attached to thoracic vertebrae (dorsally) and connected to the sternum (ventrally) via hyaline cartilage. 

False rib- 8^th, 9^th, and 10^th pairs of ribs are false ribs as they are not attached to the sternum (ventrally), but connected to the seventh rib via hyaline cartilage.

 Floating rib- Last two pairs of ribs are floating ribs as they are not connected to the sternum.

The rib cage image is shown below.

Final Answer: Hence, the correct answer is (D) 12 pairs.