The organism labelled 2 diverged first.
The correct answer is option b.
Step-by-step explanation:
The arrows in the diagram indicates the timeline. The branching point shows the event of divergence in a species.
From the diagram the divergence or internal node is shown at point C.
At point C, 2 and 3 are the new species. C is the recent ancestor of the species 2 and 3.
The ancestors of organism 2 diverged first because the timeline is also short in case of species 2.
the C internode or recent ancestor diverged in to 2 different species 2 and 3.