SI: Iguanodon was one of the first dinosaurs to be scientifically described. S6 : This quadrupedal dinosaur lived about 70 million years ago and its fossils are found in many parts of England, Europe, Asia and North Africa. P : These teeth formed a dental battery in which replacing teeth were constantly growing. Q : The fore limbs were slightly larger than other members of its group known as Omithischia. R : It had numerous teeth in the sides of the jaws, arranged in rows. S : It was about 40 feet in length. The proper sequence should be
- AQ S R P
- BS R P Q
- CR Q P S
- DP Q S R
Explanation
S gives the general fact first: about 40 feet in length. R describes the numerous teeth arranged in rows. P refers back with 'these teeth': they formed a dental battery of constantly replacing teeth. Q adds the fore limbs, larger than other Ornithischia. S6 summarizes: quadrupedal, 70 million years old, fossils across continents. Hence SRPQ, i.e. option B.