Explanation:
The longest water tunnel in Pakistan is the Neelum-Jhelum Hydropower Tunnel, which is 68 km long (including 47 km of tunnels).
- Warsak (A) – Warsak Dam has tunnels, but they are not the longest.
- Khojak (B) – Khojak Tunnel is a railway tunnel, not a water tunnel.
- Lowari (C) – Lowari Tunnel is a road tunnel, not a water tunnel.
- None of these (D) – ✅ Correct answer, because Neelum-Jhelum Hydropower Tunnel is the longest water tunnel, and it is not listed in the options.