High stringency in nucleic acid hybridization is characterized by which of the following conditions?

High stringency in nucleic acid hybridization refers to conditions that promote more specific binding between complementary nucleic acid sequences while minimizing non-specific interactions. This is typically achieved through the combination of elevated temperatures, reduced salt concentrations, and possibly the addition of components like formamide, which destabilize mismatched duplexes.

Under high temperature conditions, the stability of the hybridized DNA or RNA is affected, leading to the denaturation of any non-perfectly matched strands. A lower salt concentration contributes to the weakening of ionic interactions that stabilize hybrid duplexes, further ensuring that only perfectly matched sequences remain hybridized. The inclusion of a substance like formamide can disrupt hydrogen bonding to some extent, thus helping to enhance stringency.

For these reasons, high temperature and low salt concentration, along with the presence of formamide, effectively support specific hybridization conditions, making this option the correct choice for high stringency.