**Explanation:**

The IUPAC name of chloroform is trichloromethane. Let's break down the name and understand why it is called trichloromethane.

**1. Basic Structure:**
The basic structure of chloroform consists of a single carbon atom bonded to three chlorine atoms and one hydrogen atom. This can be represented as CHCl3.

**2. Naming Rules:**
According to the IUPAC naming rules for organic compounds, the longest carbon chain in the structure should be identified. In the case of chloroform, there is only one carbon atom, so the longest chain is just one carbon long.

**3. Naming Prefixes:**
The prefixes used in IUPAC nomenclature indicate the number of substituents attached to the main carbon chain. Here, the prefix "tri-" is used because there are three chlorine atoms attached to the carbon atom.

**4. Naming Suffix:**
The suffix in the IUPAC name indicates the functional group present in the compound. Since chloroform contains a single carbon atom bonded to three chlorine atoms, it is classified as a halomethane. Therefore, the suffix used is "-ane."

**Putting it all together:**
Based on the above rules, the IUPAC name for chloroform is trichloromethane. The prefix "tri-" indicates the presence of three chlorine substituents, and the suffix "-ane" indicates that it is a halomethane compound.

Therefore, the correct answer is option **B) Trichloromethane**.