The correct answer is option 'B' - Strait of Hormuz.

Explanation:
The shortest route for the ship to travel from Mumbai to the United Kingdom would be to take the Suez Canal route. Let's analyze each of the given options and why they would or would not be encountered on this route:

a) Great Bitter Lake:
The Great Bitter Lake is a saltwater lake located in the middle of the Suez Canal. Ships passing through the Suez Canal may encounter this lake as it is a part of the canal system. Therefore, it is possible for the ship to encounter the Great Bitter Lake on its journey from Mumbai to the United Kingdom.

b) Strait of Hormuz:
The Strait of Hormuz is a narrow waterway located between the Persian Gulf and the Gulf of Oman. However, the shortest route from Mumbai to the United Kingdom does not require passing through the Strait of Hormuz. The ship would be taking the Suez Canal route, which bypasses the Strait of Hormuz. Therefore, the ship would not encounter the Strait of Hormuz on its journey.

c) Gulf of Aden:
The Gulf of Aden is a body of water located in the Arabian Sea between Yemen and Somalia. The Suez Canal route does pass through the Gulf of Aden, so the ship would encounter it on its journey from Mumbai to the United Kingdom.

d) Strait of Gibraltar:
The Strait of Gibraltar is a narrow waterway located between the Atlantic Ocean and the Mediterranean Sea. While the ship would not encounter the Strait of Gibraltar on its journey from Mumbai to the United Kingdom, it would encounter it on its return journey from the United Kingdom to Mumbai as the ship would follow the same route in reverse.

In conclusion, the ship traveling from Mumbai to the United Kingdom by the shortest route possible would not encounter the Strait of Hormuz, making option 'B' the correct answer.