One should make (a)/ his best efforts if one wishes to achieve (b)/ success in this organisation.(c) / No error (d)

Question in this section has a sentence with three underlined parts labelled (a), (b) and (c). Read each sentence to find out whether there is any error in any underlined part and indicate your answer in the Answer Sheet against the corresponding letter i.e. (a) or (b) or (c). If you find no error, your answer should be indicated as (d). Please convey(a)/ my best wishes (b)/ back to your parents. (c)/ No error (d)