Which is a complex sentence?
a)
the nike shoes were the most expensive pair of sneakers in the whole store.
b)
some of the natives thought that having a photograph taken also stole a person's soul.
c)
janet was embarrassed by her brother's performance, but she stayed for the whole game anyway.
d)
the rebels knew that they didn't have a chance, and after much debate, they decided to surrender.

B)
Some of the natives thought that having a photograph taken also stole a person's soul.

Complex sentences contain one independent clause and a dependent clause.

Another,
“This violent weather produces a mass of warm, humid air that rises quickly, and more warm air rushes in to replace it” is a compound-complex sentence. So the correct option for the given question is option “c”. A compound-complex sentence is a sentence that is made up of one or more than one dependent clauses and two independent clauses.  These kind of sentences are very common in English but special care should be taken while writing such type of complicated sentences.