The correct option is B 2, 4- dioxohexanoic acid
For naming the given compound ; H3C−CH2−CO−CH2−CO−COOH, the following steps are followed:
i) The parent chain consists of six carbon atoms and the primary functional group is -COOH , thus the suffix -oic acid.
ii) The two secondary functional groups are -CO, thus the prefix -oxo is used for them.
iii) Numbering the compound is done from right to left, as lowest number is given to the -COOH group and also in accordance with the least sum rule for secondary functional groups.
Thus the name of the compound is 2,4-dioxohexanoic acid