Is dark reaction autotrophic or heterotrophic

Autotrophic.

Dark reaction happens in the photosynthetic process of plants or autotrophs.
(a) A giant redwood tree = Autotroph
(b) A spider = Heterotroph
(c) A rose bush = Autotroph
(d) A mushroom = Heterotroph
(e) A blue whale = Heterotroph
Autrophs are the organisms that have the capacity to form their own food from inorganic substances like the carbon dioxide. 
Heterotrophs are the organisms that cannot produce their own food but depends on other animals or plants for their nutritional needs.