to show a clean pair of heels : to escape by superior speed; to outrun.
● Sam showed them all a clean pair of heels as he raced for the finishing line. The best option is to escape.

Correct Option: B

to show a clean pair of heels : to escape by superior speed; to outrun.
● Sam showed them all a clean pair of heels as he raced for the finishing line. The best option is to escape.

to flog a dead horse : to waste your effort by trying to do something that is no longer possible
● He was warned again and again, but now I think there is no use flogging a dead horse. The best option is to attempt to do the impossible.

Correct Option: B

to flog a dead horse : to waste your effort by trying to do something that is no longer possible
● He was warned again and again, but now I think there is no use flogging a dead horse. The best option is to attempt to do the impossible.

to strain every nerve : to try as hard as you can to do something
● I was straining every nerve to catch what they were saying. The best option is to make utmost efforts.

Correct Option: A

to strain every nerve : to try as hard as you can to do something
● I was straining every nerve to catch what they were saying. The best option is to make utmost efforts.

to bite the dust : to fail; to be defeated or destroyed; to die
● The soldier was too young to bite the dust. (to die) None of the above

Correct Option: D

to bite the dust : to fail; to be defeated or destroyed; to die
● The soldier was too young to bite the dust. (to die) None of the above

to take to one’s heels : to run away from somebody/something
● As soon as the thief saw the police, he took to his heels. The best option is to run away.

Correct Option: B

to take to one’s heels : to run away from somebody/something
● As soon as the thief saw the police, he took to his heels. The best option is to run away.