org-babel-default-header-args

org-babel-default-header-args is a variable defined in `ob-core.el'.
Its value is

((:session . "none")
 (:results . "replace")
 (:exports . "code")
 (:cache . "no")
 (:noweb . "no")
 (:hlines . "no")
 (:tangle . "no"))

Documentation:
Default arguments to use when evaluating a source block.