Which hybridization condition allows high base pair mismatching in a duplex structure?

The correct choice points to low stringency hybridization conditions, which are characterized by weaker binding affinities between complementary base pairs. In these conditions, the temperature and salt concentration are adjusted to allow for more flexibility in base pairing. This means that mismatched pairs can still hybridize, as the lower stability of the duplex promotes the formation of hybrids between sequences that do not perfectly match.

In contrast, high stringency conditions involve increased temperature and/or reduced salt concentrations, which enhance the specificity of hybridization. Under high stringency, only perfectly matched sequences are able to form stable duplexes, thereby preventing mismatches from being tolerated.

Medium stringency conditions fall between low and high stringency, allowing for some level of mismatching, but not as permissive as low stringency. No stringency conditions would allow any and all sequences to hybridize without concern for matching, but this term is less commonly used in practical applications compared to the other levels of stringency.

Thus, the ability of low stringency conditions to accommodate greater base pair mismatches is what makes them the correct response to this question.