You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Greece

Context:
Rebetiko, initially a music associated with the lower classes, later (and especially after the population exchange between Greece and Turkey) reached greater general acceptance as the rough edges of its overt subcultural character were softened and polished, sometimes to the point of unrecognizability. It was the base of the later laïkó (song of the people). The leading performers of the genre include Apostolos Kaldaras, Grigoris Bithikotsis, Stelios Kazantzidis, George Dalaras, Haris Alexiou and Glykeria.

Question:
One of the leading performers of the laiko genre is who?

Apostolos Kaldaras