## **Core Concept**
The question tests understanding of the pharmacological modulation of mast cell responses, specifically the release of histamine and leukotrienes, which are key mediators in allergic reactions. Mast cells play a crucial role in allergic inflammation, and their degranulation leads to the release of various chemical mediators.

## **Why the Correct Answer is Right**
Corticosteroids, such as prednisolone, are known to have anti-inflammatory effects, including the prevention of the release of histamine and leukotrienes from mast cells. They work by inducing the synthesis of lipocortins, which inhibit phospholipase A2, an enzyme necessary for the production of arachidonic acid—the precursor for leukotrienes. Additionally, corticosteroids have a genomic effect that leads to the suppression of the synthesis of inflammatory mediators.

## **Why Each Wrong Option is Incorrect**
- **Option A:** While antihistamines can block the effects of histamine on target organs, they do not prevent the release of histamine and leukotrienes from mast cells.
- **Option B:** This option is not provided, but typically, drugs like cromolyn sodium prevent mast cell degranulation. However, without the specific option, we focus on the mechanism related to corticosteroids.
- **Option D:** Without the specific drug listed, it's hard to directly refute, but generally, other classes like beta-agonists or theophylline have different primary mechanisms of action and do not primarily prevent mast cell degranulation or mediator release.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that corticosteroids are highly effective in reducing inflammation and are used in a wide range of conditions, including severe allergic reactions. They are particularly useful because they can prevent the synthesis of pro-inflammatory mediators, making them more effective than drugs that only block the action of these mediators.

## **Correct Answer:** . Corticosteroids.