**Core Concept**
Electron microscopy is a technique used to produce high-resolution images of the ultrastructure of cells and tissues. It provides detailed information about the morphology and organization of cellular components, such as organelles, membranes, and proteins.

**Why the Correct Answer is Right**
Electron microscopy is widely used in various fields of biomedical research, including structural biology, cell biology, and pathology. It is used to study the fine details of cellular components, such as the arrangement of proteins in membranes, the structure of organelles, and the morphology of viruses and bacteria. The technique is particularly useful for visualizing structures that are too small to be resolved by light microscopy.

**Why Each Wrong Option is Incorrect**

* **Option A:** Electron microscopy is indeed used for studying the ultrastructure of cells and tissues, so this option is incorrect.
* **Option B:** Electron microscopy can be used to study the morphology of viruses and bacteria, making this option incorrect.
* **Option C:** Electron microscopy is used to study the fine details of cellular components, including proteins, membranes, and organelles, so this option is incorrect.

**Clinical Pearl / High-Yield Fact**
Electron microscopy is particularly useful for studying the ultrastructure of cells and tissues that are difficult to study using light microscopy, such as the morphology of viruses and bacteria. It is also used to study the fine details of cellular components, including proteins, membranes, and organelles.

**Correct Answer:** A.