Explanation:

Introduction:
A domain name is a unique address that identifies a website on the internet. It is used to locate and access websites. Domain names consist of two or more parts, separated by periods (dots). In this question, we are asked to identify the correct option regarding the separation of parts in a domain name.

Explanation:
The correct answer is option B, which states that domain names are separated by periods (dots). Let's understand why this is the correct answer.

Domain Name Structure:
A domain name is composed of different parts that provide specific information about the website. These parts are separated by periods (dots). The structure of a domain name is as follows:

1. Subdomain: The subdomain is an optional part of a domain name. It appears before the main domain name and is separated by a period. For example, in the domain name "blog.example.com," "blog" is the subdomain.

2. Main Domain: The main domain is the primary part of a domain name. It represents the organization or entity that owns the website. For example, in the domain name "blog.example.com," "example" is the main domain.

3. Top-Level Domain (TLD): The top-level domain is the last part of a domain name. It represents the type or category of the website. Common TLDs include .com, .org, .net, and .edu. For example, in the domain name "blog.example.com," ".com" is the top-level domain.

Separation of Parts:
To separate these different parts and create a valid domain name, periods (dots) are used. The subdomain is separated from the main domain by a period, and the main domain is separated from the TLD by another period. This creates a hierarchical structure that helps in organizing and identifying websites on the internet.

Conclusion:
In conclusion, domain names always have two or more parts, and these parts are separated by periods (dots). The correct option among the given choices is B. Understanding the structure and separation of parts in a domain name is essential for correctly identifying and accessing websites on the internet.