Question: Pentatonix, the five-member American a cappella group lost their vocalist Avi Kaplan in 2017 at the same time as their tribute to which group received over 250 million views?
Sentence (from "Pentatonix"): Pentatonix (abbreviated PTX) is a five-member American a cappella group from Arlington, Texas, consisting of vocalists Scott Hoying, Mitch Grassi, Kirstin Maldonado, Avi Kaplan, and Kevin Olusola.
Relevant evidence: No