Which of the following type of cells lack a nucleus?

1. Lymphocyte

2. Neutrophils

3. Eosinophils

4. Erythrocytes

(a) RBCs (Red Blood Corpuscles) in humans lack nucleus. Absence of nucleus in the cell reduces the O2 consumption by the cell in various cellular activities. Therefore, the cell is able to transport maximum amount of O2 to other cells of the body.
Other cells like neutrophils, eosinophils and monocytes possess nucleus of varied shape and size as shown below.