Identify the error: The data is being analysed carefully.

The correct answer is No error. This sentence is grammatically correct. The word "data" can be treated as either a plural noun (the Latin plural of "datum") or, increasingly in modern English, as a singular mass noun, especially in everyday usage and certain scientific or technical contexts. When treated as a singular mass noun, it takes a singular verb, such as "is." Therefore, "The data is being analysed carefully" is perfectly acceptable. The sentence is also correctly structured in the present continuous passive voice ("is being analysed"), indicating an ongoing action being performed on the data. The adverb "carefully" correctly modifies the verb "analysed," describing how the analysis is being conducted. There are no subject-verb agreement issues, tense errors, or incorrect word choices. This reflects the evolving usage of "data" in contemporary English, where its singular form is widely accepted.