I’m not a hundred and ten percent sure on this (my Spanish is a bit rusty) but I believe the answer would be something like Es la una (if it is in the one o’clock hour)
That is because "ropa" which means clothes or clothing is a feminine noun in the Spanish language, so when the first person says that they have to buy clothes, the second one uses "la" because "la" is used for the feminine "ropa". "lo" would be for masculine while "los" would be for masculine plural". <span />
