Symbiosis National Aptitude Test SNAP 2017 Paper

The first clause of the sentence declares that the job is tough; so, the likelihood of it ending in a 'fiasco'(second clause) is high.
Hence, the second clause should either say, that 'therefore, it always/ usually/ invariably/ regularly ends in a fiasco'; or, that 'nonetheless/yet/surprisingly, it never /seldom /rarely/ hardly ends in a fiasco'. Options c is the only one with the right combination of words that convey the appropriate meaning.