Question

Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error, if any, will be in one part of the sentence. The letter of that part is the answer. If there is ‘No error’, the answer is (5). (Ignore errors of punctuation, if any). The government has announced new guidelines (

Q: Answer-Read the sentence to find out whether there is any grammatical or idiomatic error in it. The error,...

In D, replace persists with persist. The subject of the sentence is implementation challenges, which is plural. Therefore, the verb should also be in the plural form, i.e., persist. The sentence would then read The government has announced new guidelines to improve air quality in urban areas, but the effectiveness of these measures remains to be seen as implementation challenges persist. Therefore, D is the correct answer.