Each item in this section has a sentence with three underlined parts, labelled as (a), (b) and (c). Read each sentence to determine whether there is any error in any underlined part and indicate your response on the Answer Sheet against the corresponding letter, i.e., (a) or (b) or (c). If you find no error, your response should be indicated as (d).

(a) Electricity companies are (b) working throughout (c) days and nights to repair the damage. (d) No error.