Question

what can mrna do that dna cannot? enter the nucleus copy itself leave the nucleus

Explanation:

To determine what mRNA can do that DNA cannot, we analyze the options:

• "enter the nucleus": DNA is already in the nucleus, and mRNA is transcribed from DNA in the nucleus, so mRNA doesn't enter the nucleus (DNA is already there).
• "copy itself": DNA can replicate (copy itself), while mRNA is typically transcribed from DNA and doesn't have a main role of copying itself in the same way.
• "leave the nucleus": DNA is confined within the nucleus (in eukaryotic cells) and cannot leave. mRNA, after transcription in the nucleus, is transported to the cytoplasm (leaves the nucleus) for translation. So mRNA can leave the nucleus, which DNA cannot.

Answer:

leave the nucleus (the option "leave the nucleus")