Each part of this scenario describes an injury with its own mechanism and telltale signs. Working through the case line by line, and ruling out what each injury is NOT, gives the four answers.
(i) Rohan's ankle: He felt "unbearable pain" and swelling right after a sudden collision, with no mention of a break or a dislocated joint shape. A dislocation would show a visibly deformed joint, and a fracture would usually be accompanied by an inability to bear any weight at all along with a grating sensation. What's left, given a twisted joint with pain and swelling but no deformity, is a stretched or torn ligament around the ankle joint, i.e. a sprain.
(ii) Sachin's forehead: The coach saw "a collection of blood outside the blood vessel," with the skin intact. Since the blood has leaked into the surrounding tissue without the skin being cut, this rules out a wound (open bleeding) and an abrasion (scraped skin, not pooled blood). This blood collection under unbroken skin is a contusion.
(iii) Abrasion symptom: An abrasion happens when skin is dragged across a rough surface, for example sliding on turf. This mechanism does not tear deep tissue or break a bone, it only scrapes off the outer skin layer. So the matching symptom is the rubbing away of the upper layer of the epidermis (scraped skin), not bruising or bone-related pain.
(iv) Soft bone bending: A complete fracture in an adult bone usually snaps into two pieces. But children's bones are still flexible and contain more collagen, so under stress the bone can bend and crack partially without fully separating. This partial bend-and-crack pattern, typical of a young player's bones, is known as a greenstick fracture.
So, the correct answers are (i) Sprain, (ii) Contusion, (iii) Rubbing away of the upper layer of the epidermis, (iv) Greenstick fracture.

