Answer: Option A
Answer: (a)The ‘hard’ means ‘tough or requiring a lot of efforts’ whereas ‘Hardly’ means ‘not enough’. The given sentence is written to express a sense that a lot of effort led to his success. Therefore, the obvious word should be ‘hard’ not ‘hardly’. Options (a) and (b) are ruled out, because, in these two options, ‘hardly’ have been used. Option (c) has ‘he had tried hard’. This option is obsolutely correct. Therefore we should opt for this option.