premise: Two girls (one dressed in blue, and one dressed in pink) are racing one another on rollerskates. hypothesis: The girls are racing on jetskis.
contradiction: They contradict each other, as one says they are on jetskis and the other says they are on rollerskates.|contradiction: The girls can not be racing on jet skis if they are racing in rollerskates.|contradiction: The girls are either racing on jetskis or on rollerskates.