Which of the following for an object should be known to calculate its density? the heat present in it the amount of matter in it the force of gravity acting on it the space between the object and another object

Polar bears give birth and hunt on sea ice. which of the following would polar bears survive during the melting of arctic ice? growing another layer of fur during summer migrate inland to search for different food sources staying put until the ice refreezes sticking to the usual diet of seals