Final answer:
Translation inhibition reinforces the hunchback gradient during embryonic development by preventing the translation of hunchback mRNA in certain regions of the embryo.
Step-by-step explanation:
The process that reinforces the hunchback gradient during early embryonic development is D) Translation inhibition. The regulation of hunchback mRNA involves translational control mechanisms, where entities like Nanos and Pumilio proteins bind to the hunchback mRNA, preventing its translation in the posterior part of the embryo. This process defines the gradient of the Hunchback protein, allowing it to function correctly in establishing the anterior-posterior axis of the developing embryo.