Final answer:
The major mediators released from mast cells upon degranulation include histamine, serotonin, and leukotrienes; thus, the correct answer is All of the above.
Step-by-step explanation:
The major mediators stored and released from mast cells upon degranulation are histamine, serotonin, and leukotrienes. When mast cells degranulate, they release preformed components like histamine and serotonin, which are responsible for immediate allergic reactions, along with bradykinin. In addition to these preformed mediators, activated mast cells also synthesize and release newly formed mediators such as leukotrienes and prostaglandins, which are derived from membrane arachidonic acid metabolism, as well as cytokines like tumor necrosis factor.
Therefore, the correct answer to the question regarding the major mediator/s stored and released from mast cells upon degranulation is D) All of the above.