Woolly mammoths were grass-eating mammals that resembled elephants but with heavy coats, large tusks, and small ears that made them suited for extremely cold weather of the ice age. in addition to hunting by humans, which other conditions may have caused woolly mammoths to become less reproductively successful and eventually become extinct at the end of the last ice age?

decreased grassland habitat size caused by a warmer climate
decreased mammoth predator population size caused by warmer climate
increased production of offspring adapted to the changing environment
increased genetic variation in mammoth populations in warmer latitudes