Read the following passage.

we crawled through stony ravines, over snow slopes, amidst fungi that ripped like thin bladders at our thrust, emitting a watery humour, over a perfect pavement of things like puff-balls, and beneath interminable thickets of scrub.
which is the best definition for the italicized word humour as it is used above?

bodily fluid
comply with the wishes of someone
the quality of being amusing
mood or state of mind