Explanation:

- B attends the seminar on 5th January.

- Four people attend between H and A.

- A attends just before G.

- One person attends between G and E.

- D attends after H, and three people separate F and D.

- C doesn't attend in February.

Let's construct the sequence:

1. B - 5th January (given).

2. The next possible position for H is 11th January or 5th February.

3. If H is on 5th February, then A will be on 11th March (4 people after).

4. Hence, G will be on 11th March.

5. Then E takes 5th March (1 between G and E).

6. Since F is linked with D with 3 between, try placing F on 5th April and D on 11th April.

7. Since C is not in February, the only date left is 11th February.

This satisfies all conditions. Hence, G attends the seminar in April.

- Correct Answer is: Option 3: G