Answer:
6
Step-by-step explanation:
The Lewis structure represents the valence electrons at the atoms, which ones are shared and the lone pairs. Carbon is at group 4 at the periodic table, and so has 4 electrons in the valence shell; oxygen is at group 6, and so has 6 electrons at the valence shell.
That compound is an exception of the octet rule. A triple bond is done between the atoms, and so, 3 electrons of carbon are shared and 3 electrons of oxygen are shared. Thus, there are 6 bonding electrons, as shown below in red.