Final answer:
Oasis became a temporary quartet during their 1996 performance on 'MTV Unplugged' due to Liam Gallagher's laryngitis, with Noel Gallagher taking the lead vocals.
Step-by-step explanation:
The quintet that became a temporary quartet on "MTV Unplugged" in 1996 when singer Liam Gallagher had laryngitis is Oasis. Oasis is known for its significant contribution to the Britpop movement and the band's sibling rivalry between Liam Gallagher and his brother Noel. Despite Liam's absence due to illness during the unplugged performance, Noel Gallagher stepped up to perform lead vocals, demonstrating the band's adaptability and commitment to their music.