/sci/ - Science & Math

What is c) is asking here. Is it asking for a sequence that is cauchy wrt both metrics but only convergent wrt one metric? In that case can I just use X={1/n for natural n} and my sequence just be X, then the usual metric is not convergent in X wrt usual metric since 0 is not in X but it is convergent in X wrt discrete metric since 1 is in X. Am I think of this right or am i misunderstanding and its asking something other than a sequence that is cauchy in both but convergent in one?