Which one of the following cities is associated with the river Mekong ?

Phnom-Penh cities is associated with the river Mekong. The river flows through Laos, Cambodia, and Vietnam before draining into the South China Sea south of Ho Chi Minh City (formerly Saigon). Vientiane (Viangchan), the capital of Laos, and Phnom Penh, the capital of Cambodia, both stand on its banks.