Which one among the following countries of Asia is land-locked ?

Which one among the following countries of Asia is land-locked ?

Vietnam
Cambodia
Laos
Thailand
This question was previously asked in
UPSC CAPF – 2014
A landlocked country is a sovereign state entirely enclosed by land, having no access to the open sea.
Among the given options, Laos is the only country that does not have a coastline. It is bordered by China, Vietnam, Cambodia, Thailand, and Myanmar.
– Vietnam has a long coastline on the South China Sea.
– Cambodia has a coastline on the Gulf of Thailand.
– Thailand has coastlines on the Gulf of Thailand and the Andaman Sea.
– Other landlocked countries in Asia include Afghanistan, Armenia, Azerbaijan (partially bordered by the Caspian Sea, sometimes considered landlocked), Bhutan, Kazakhstan, Kyrgyzstan, Mongolia, Nepal, Tajikistan, Turkmenistan, Uzbekistan.