**Core Concept**
Mammography is a crucial imaging modality for breast cancer screening and diagnosis, relying on the detection of subtle changes in breast tissue density, calcifications, and masses.

**Why the Correct Answer is Right**
The most sensitive and specific mammographic finding for breast carcinoma is the presence of **microcalcifications**. These tiny calcium deposits can be an early sign of breast cancer, often appearing before a palpable mass or other noticeable changes. Microcalcifications are usually associated with ductal carcinoma in situ (DCIS) or invasive ductal carcinoma, and their presence warrants further investigation, such as biopsy.

**Why Each Wrong Option is Incorrect**
**Option A:** Ultrasound is useful for evaluating palpable breast masses and differentiating cystic from solid lesions, but it is not the most sensitive or specific investigation for carcinoma breast.

**Option B:** Magnetic Resonance Imaging (MRI) is highly sensitive for breast cancer, particularly in dense breast tissue, but it is not the first-line investigation for screening or diagnosis due to cost and availability constraints.

**Option C:** Clinical examination is essential for detecting palpable breast masses, but it is not the most sensitive or specific method for identifying carcinoma breast, as many cancers are non-palpable.

**Clinical Pearl / High-Yield Fact**
A key feature of malignant microcalcifications is their **clustered, linear, or segmental distribution**. This pattern is more suggestive of cancer than scattered or diffuse calcifications.

**Correct Answer: D. Mammography. Mammography is the most sensitive and specific investigation for carcinoma breast.**