Arrange the following events occurring in the ovary in the CORRECT sequence
a. The antrum is formed .
b. Formation of a first tiny polar body .
c. The primary follicles get surrounded by more and more layers of granulosa cells.
d. The primary oocytes is arrested in prophase - I of the meiotic division .

Options

A. d,a b and c
B. a,c,d and b
C. d,a, c and b
D. d ,c ,a and b

Answer

To arrange the events occurring in the ovary in the correct sequence, we need to understand the process of oogenesis, which involves several stages of development of the oocyte. Here’s the step-by-step solution:

1. **Primary Oocyte Arrested in Prophase I (D)**: The process of oogenesis begins with the formation of oogonia, which undergo mitosis to become primary oocytes. These primary oocytes enter the first meiotic division but are arrested in prophase I. This is the first event in the sequence.

2. **Primary Follicles Surrounded by Granulosa Cells (C)**: After the primary oocytes are formed, they get surrounded by a layer of granulosa cells, transforming into primary follicles. This is the second event in the sequence.

3. **Formation of Antrum (A)**: As the primary follicles develop further, they can transform into secondary follicles and eventually into tertiary follicles. The tertiary follicles are characterized by the formation of a fluid-filled cavity known as the antrum. This is the third event in the sequence.

4. **Formation of First Tiny Polar Body (B)**: Finally, when the primary oocyte completes its first meiotic division, it results in the formation of a secondary oocyte and a tiny polar body. This is the last event in the sequence.

Putting it all together, the correct sequence of events is:
1. D - The primary oocyte is arrested in prophase I of meiotic division.
2. C - The primary follicles get surrounded by more layers of granulosa cells.
3. A - The antrum is formed.
4. B - Formation of the first tiny polar body.

### Final Sequence:
**D → C → A → B**