Which of the following is a creole language?

A creole language refers to a stable, fully developed natural language that arises from the mixing of two or more languages. This typically occurs in a context where speakers of different native languages need to communicate, such as during colonization or in trade situations. Swahili is classified as a creole language due to its historical development, which involved the fusion of Bantu languages with Arabic and other influences, primarily as a result of trade along the East African coast.

The other languages mentioned are not considered creole languages. Spanish, English, and German are all classified as standard languages with roots in Indo-European languages, each developing independently rather than as a result of mixing multiple distinct linguistic traditions into a new hybrid form.