The earthworm has no bones but there is a series of muscular rings all along its body, which it uses for locomotion. Given below are the various steps of its locomotion. Arrange them in sequence and select the correct option.
(i) It shortens the body by muscle contraction and pulls its rear-end forward.
(ii) It fixes the front end and releases the near end.
(iii) It fixes its rear portion to the ground with the help of tiny bristles.
(iv) It extends the front part of its body by muscle expansion.

Options

A. (iv) `to` (iii) `to` (ii) `to` (i)
B. (iii) `to` (iv) `to` (ii) `to` (i)
C. (i) `to` (ii) `to` (iii) `to` (iv)
D. (ii) `to` (iii) `to` (iv) `to` (i)

Explanation

To arrange the steps of locomotion of an earthworm in the correct sequence, we can analyze the process as follows:

1. **Step 1: Fixing the Rear Portion**
The earthworm first fixes its rear portion to the ground with the help of tiny bristles. This is crucial as it provides a stable point from which the worm can move forward.

2. **Step 2: Extending the Front Part**
Next, the earthworm extends the front part of its body by muscle expansion. This allows the worm to reach forward and prepare for the next movement.

3. **Step 3: Fixing the Front End and Releasing the Rear End**
After extending the front, the earthworm then fixes its front end to the ground and releases its rear end. This action helps in pulling the body forward.

4. **Step 4: Shortening the Body**
Finally, the earthworm shortens its body by muscle contraction, pulling its rear end forward to complete the movement.

Thus, the correct sequence of locomotion steps for the earthworm is:
(iii) → (iv) → (ii) → (i)