In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.

Q: Question: Histone deacetylases (HDAC) promote:
Options: <0> A less condensed chromatin. <1> A weaker link between histones and DNA in nucleosomes. <2> The acetylation of lysine residues in histones. <3> That the poly (A) tail of the histone messenger RNAs be more extensive. <4> The termination of the transcription and the genetic silencing.

A: pharmacology
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Q: Question: The reaction of 3-nitrobenzaldehyde with NaBH 4 in aqueous methanol gives:
Options: <0> 3-Aminobenzaldehyde. <1> 3-nitrobenzoic acid. <2> 1-Methyl-3-nitrobenzene. <3> 3-Nitrobenzoate sodium. <4> (3-Nitrophenyl) methanol.

A: chemistry
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Q: Question: In the synthesis of DNA, the quinolones act:
Options: <0> Joining the double helix and thus blocking the progress of the replication fork. <1> Interlacing in the double helix and thus causing errors in the transcription. <2> On DNA gyrase. <3> As nucleotide analogs that are incorporated into DNA. <4> About DNA polymerases.

A:
biology
****