Question: Vaka is the common name for a track and lead single from which band that takes its name from the frontman's sister, Sigurrós Elín?
Sentence (from "List of songs written by Bruno Mars"): American singer-songwriter Bruno Mars has written and recorded songs for his studio albums, "Doo-Wops & Hooligans" (2010) and "Unorthodox Jukebox" (2012), and has written songs for other singers.
Relevant evidence: No