Given India is UTC+5.5 and China is UTC+8, plus many other large countries are outside that range (Indonesia, Japan, Bangladesh, Mexico, Phillipines) I think you need to stretch it a bit
UTC+8 is all of China and UTC+5.5 is all of India, and in between are high population countries like Indonesia, Philippines, Vietnam, so UTC+5.5 to UTC+8 has to be included.
UTC+11 to UTC-8.5 is the Pacific Ocean and has maybe 10 million people total, while UTC+0 has >100 million in UK, Portugal and part of Western Africa so UTC+0 must be part of the range.
That only leaves the choice between UTC-1/2 and UTC+9/10. UTC-1 and UTC-2 have under a million with only a few small islands while UTC+10 has most of Papua New Guinea with 6 million.