Given below are three sentences which use a common word highlighted. Find out the correct pair of the sentences that use the word correctly. (i)The robust economy of the country has helped it recover quickly from the recession. (ii) The restaurant received robust reviews for its new vegetarian menu. (iii) The robust of the machine broke down after a few years of use.

Explanation: In sentence i, "robust" is used correctly to refer to something strong or healthy, in this case, the economy of the country. In sentence ii, "robust" is used incorrectly because the word "robust" usually refers to something strong or sturdy, not necessarily to the reviews of a restaurant. It should be "positive" or "favorable" reviews, not "robust." In sentence iii, "robust" is used incorrectly. The phrase should be "the robustness of the machine," referring to the strength or durability of the machine.