In the following questions, a part of the sentence may contain an error. Identify the part that contains the error. If the sentence is grammatically correct, choose the option corresponding to “No error”. Nearly two-thirds of the drinking water supplied through / the municipal pipes are contaminated with excess fluoride and iron, which is why so many people in our area / have started buying packaged water instead.

The error is related to subject–verb agreement. Subject: → “drinking water” “Water” is an uncountable singular noun. Thus, the verb should also be singular: → “is contaminated” NOT → “are contaminated” Correct sentence: “Nearly two-thirds of the drinking water supplied through the municipal pipes is contaminated…” Why the confusion occurs: Even though “two-thirds” appears plural, the actual noun being quantified is “water,” which is singular and uncountable. Other parts: (b) grammatically correct (c) correct introductory structure (d) logically coherent clause Hence, option (a).