[Answer] Who's known for songs "Let Her Go" and "Holes?"

Step 1 : Introduction to the question "Who's known for songs "Let Her Go" and "Holes?""

...Mike Rosenberg, known by his stage name, Passenger, wrote his multi-platinum hit "Let Her Go" in about 45 minutes when playing to a small crowd of 25 in rural Australia. The song sold over six million downloads worldwide, making Passenger a well-known name worldwide in just a matter of months. He went from playing small bar venues to opening on tour with Ed Sheeran. The singer-songwriter continues to write a variety of music, even songs that aren't, as he puts it, "really sad love songs about my ex-girlfriend." Source: AmericanSongwriter.com

[Answer] 10. 'Grease', 'Phenomenon', 'Look Who's Talking'.

Step 1 : Introduction to the question "10. 'Grease', 'Phenomenon', 'Look Who's Talking'."

...1. Olivia Newton-John 2. John Travolta 3. Robert Duvall 4. Kirstie Alley

[Ans] Which comedy duo was famous for their “Who’s on First” routine?

Step 1 : Introduction to the question "Which comedy duo was famous for their “Who’s on First” routine?"

The first baseman is named "Who"; thus, the utterance "Who's on first" is ambiguous between the question ("Which person is the first baseman?") and the answer ("The name of the first baseman is 'Who'").