Which is more natural? "his" or "the"?
ex)He talked with his right hand in his(the) pocket.
(Not just 'more natural' - the version with 'the' is almost always wrong. The only exceptions that come to mind are if the pocket has been given special focus [as in 'There was an ominous bulge in his coat-pocket, and he talked with his right hand in the pocket all the time'] or if the 'pocket' is metaphorical - as when the speaker is resting his hand on a pool table. These cases are so rare that is safe to just ignore them and say 'he talked with his hand in the pocket' is wrong.)