Correct sequence of follicular development:
(a) Graafian follicle (Mature tertiary)
(b) Primary follicle
(c) Tertiary follicle
(d) Secondary follicle

Answer

To determine the correct sequence of follicular development, we need to understand the stages of folliculogenesis. Here’s the step-by-step breakdown:

### Step 1: Identify the Starting Point
- The development of ovarian follicles begins with the **primordial follicle**. However, since it is not listed in the options, we start with the **primary follicle**.

### Step 2: Sequence of Development
- The **primary follicle** (Option b) is the first stage we will consider.
- From the primary follicle, it develops into the **secondary follicle** (Option d).
- Next, the secondary follicle matures into the **tertiary follicle** (Option c).
- Finally, the tertiary follicle develops into the **Graafian follicle** or **mature tertiary follicle** (Option a).

### Step 3: Compile the Sequence
- The correct sequence of follicular development based on the above steps is:
1. Primary follicle (b)
2. Secondary follicle (d)
3. Tertiary follicle (c)
4. Graafian follicle (a)

### Final Answer
The correct sequence of follicular development is:
**(b) Primary follicle → (d) Secondary follicle → (c) Tertiary follicle → (a) Graafian follicle.**

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