At what temperature can DNA be stored short-term after isolation?

Correct answer: About 4°C

The governing concept is that lower temperature slows chemical reactions and nuclease activity, thereby helping preserve isolated DNA. For routine short-term storage, purified DNA is commonly kept at about 4°C, provided the sample is clean and the storage period is limited. Therefore option A is the best answer. Heating at 100°C or placing DNA in boiling water can denature or damage the molecule and is not a storage method. Leaving a tube open at room temperature increases the risk of contamination, evaporation, and degradation, so option C is also unsuitable. For longer storage, DNA is generally kept frozen, often at -20°C or lower depending on the protocol.