The correct option is A Neutrophils and basophils respectively
Most abundant and least abundant white blood cells:
There are 5 types of white blood cells: Neutrophils, basophils, eosinophils, monocytes and lymphocytes.
Among the five cells, the most abundant white blood cells are neutrophils which form 60−65% of the total WBC volume. The least abundant white blood cells are basophils which form 0.5−1% of total WBC volume.
Final answer: (B) Neutrophils and basophils respectively