One can at least argue that all of these are Chinese foods. However, if you have to say that one of these is not a Chinese food, the best answer is Laksa.
Both Peking Duck and Sweet and Sour Pork are clearly Chinese foods. Peking Duck is seen as a symbol of China and a national food. Sweet and Sour Pork is very popular in the cuisine of the Canton area of southern China. Thus, these cannot be the correct answer.
Spring rolls are not exclusively Chinese. Variations on spring rolls are eaten all over East Asia. However, they are said to have originated in China.
Laksa is a dish that is not common in China itself. Instead, it is more of a Malaysian dish. However, it has its origins with ethnic Chinese people living in Malaysia. Thus, while Laksa is arguably a Chinese dish, it is the best answer to this question.