Question: Which singer is also a guitarist, Kang Seung-yoon or Piotr Wiwczarek?
Sentence (from "Kang Seung-yoon"): Kang Seung-yoon (born (1994--) 21, 1994 ), known as Seungyoon, is a South Korean singer-songwriter, record producer, actor, and leader of boy group Winner.
Relevant evidence: Yes