Given below are the steps involved in oogenesis . Arrange them in proper sequence and select the correct option.
1. Formation of primary follicle due to development of granulosa cells.
2 Division of oogonia and formation of the primary oocyte.
3. Formation of follicles having antrum .
4. Formation of secondary follicles.
5. An unequal division leading to the formation of secondary oocyte i.e. ovum and the first polar body .

Options

A. 1, 3 ,4 ,2 ,5
B. 2 ,1 ,4, 3, 5
C. 3, 1 ,2 ,4, 5
D. 1, 5, 3, 2 ,4

Answer

To arrange the steps involved in oogenesis in the correct sequence, we can follow the developmental process of oocytes in the ovaries. Here’s the step-by-step solution:

### Step-by-Step Solution:

1. **Division of oogonia and formation of the primary oocyte (Step 2)**: Oogenesis begins with the division of oogonia, which are the precursor cells. These cells undergo mitosis to form primary oocytes.

2. **Formation of primary follicle due to development of granulosa cells (Step 1)**: Each primary oocyte is surrounded by a layer of granulosa cells, leading to the formation of a primary follicle.

3. **Formation of secondary follicles (Step 4)**: As the primary follicles mature, they develop into secondary follicles, which have additional layers of granulosa cells.

4. **Formation of follicles having antrum (Step 3)**: The secondary follicles continue to develop and form a fluid-filled cavity known as the antrum, resulting in the tertiary or Graafian follicle.

5. **Unequal division leading to the formation of secondary oocyte (i.e., ovum) and the first polar body (Step 5)**: Finally, the primary oocyte undergoes meiosis, resulting in an unequal division that produces a secondary oocyte (the ovum) and a smaller first polar body.

### Correct Sequence:
- 2 → 1 → 4 → 3 → 5

### Answer:
The correct option is B (2, 1, 4, 3, 5).