The process depicted in the diagram is transcription because it clearly shows that an mRNA is attached to the DNA . Since we can see that two bases G and A are not yet paired we can conclude that more Bases will be added to the mRNA.
DNA is a Double helix that has a complementary DNA strand thus we can guess that the mRNA is not the integral part of the molecule but it is being synthesised from the DNA.
The 3' end of DNA is unpaired and hints that the bases will be added to 3' end of the mRNA.
