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"): Characterized by their pop-style arrangements with vocal harmonies, basslines, riffing, percussion and beatboxing, they are widely known for their covers, mostly of modern pop works or Christmas songs, sometimes in the form of medleys, along with original material.
Relevant evidence: No