Final answer:
During transcription, RNA synthesis occurs as a DNA strand is used as a template to produce messenger RNA (mRNA).
Step-by-step explanation:
The process of transcription involves the synthesis of RNA. During transcription, a DNA strand is used as a template to produce a complementary RNA strand called messenger RNA (mRNA). This step takes place in the nucleus of the cell. The other options described in the question are not directly related to the process of transcription.