**Core Concept**
The Hepatitis B vaccine is a recombinant vaccine that uses a piece of the Hepatitis B virus surface antigen (HBsAg) to stimulate an immune response. The vaccine is generally safe and effective, but there are certain contraindications to its use.

**Why the Correct Answer is Right**
The correct answer is **A. Pregnancy**. The Hepatitis B vaccine is a live, attenuated vaccine, but the Hepatitis B vaccine used in many countries is a recombinant vaccine, which is not contraindicated in pregnancy. However, the Hepatitis B vaccine is usually given to pregnant women who are at high risk of Hepatitis B infection, such as those with a history of intravenous drug abuse or who have been exposed to the virus. The main contraindication is related to the use of certain components in the vaccine, such as neomycin, which is a live bacterial product, and thimerosal, which is a mercury-containing preservative. However, the most common contraindication to the vaccine is pregnancy.

**Why Each Wrong Option is Incorrect**
* **Option B:** This option is incorrect because the Hepatitis B vaccine is not contraindicated in patients with a history of allergy to yeast. The vaccine is produced in yeast cells, but the yeast proteins are removed during the manufacturing process, making it safe for use in patients with yeast allergies.
* **Option C:** This option is incorrect because the Hepatitis B vaccine is not contraindicated in patients with a history of immunodeficiency disorders. In fact, the vaccine is often recommended for patients with immunodeficiency disorders who are at high risk of Hepatitis B infection.
* **Option D:** This option is incorrect because the Hepatitis B vaccine is not contraindicated in patients with a history of autoimmune disorders. The vaccine is generally well-tolerated and has not been associated with an increased risk of autoimmune disorders.

**Clinical Pearl / High-Yield Fact**
It's worth noting that the Hepatitis B vaccine is a recombinant vaccine, which means that it uses genetic material from the virus to stimulate an immune response. This makes it safe for use in patients with certain allergies and immunodeficiency disorders.

**Correct Answer:** A. Pregnancy