**Core Concept**
Measles vaccine is a live attenuated vaccine that is contraindicated in individuals with weakened immune systems, such as those with severe immunodeficiency diseases or taking immunosuppressive therapy. The vaccine is usually administered to children between 9-15 months of age, with a second dose given at 4-6 years of age.

**Why the Correct Answer is Right**
The measles vaccine can be safely administered within 4 weeks after receiving immunoglobulin (IG) due to the temporary suppression of the immune response to the live vaccine by IG. This allows for the administration of the vaccine in scenarios where IG is required, such as in cases of exposure to measles or in certain medical procedures. The immune system recovers from the temporary suppression within 4 weeks, allowing the vaccine to take effect.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as there is no specific time frame for administering the measles vaccine after receiving IG.
**Option B:** This option is incorrect as it does not specify a correct time frame for administering the measles vaccine after receiving IG.
**Option C:** This option is incorrect as it is too long, and the immune system would have recovered from the temporary suppression by this time.

**Clinical Pearl / High-Yield Fact**
It's essential to note that measles vaccine can be safely administered within 4 weeks after receiving IG, allowing for protection against measles in individuals who require IG for other medical reasons. This is a critical consideration in the management of measles exposure and outbreaks.

**Correct Answer:** D. 4 weeks.