The easiest way of communication among the given options is option 'A', which is E-mail. Let's explore the reasons why E-mail is considered the easiest means of communication:

1. Accessibility:
E-mail is widely accessible to almost everyone these days. As long as you have an internet connection and a device such as a computer or smartphone, you can easily send and receive emails. It is not limited by geographical boundaries or time zones, making it a convenient mode of communication.

2. Speed:
E-mail allows for instant communication as messages are delivered within seconds or minutes. This makes it ideal for situations where quick response or urgent communication is required. Unlike traditional mail, which may take days or even weeks to reach its destination, emails are delivered almost instantly.

3. Cost-effective:
E-mail is a cost-effective method of communication. Unlike the telephone, fax, or traditional mail, sending emails does not incur any additional charges. This makes it an economical choice for individuals and businesses, especially when communicating over long distances.

4. Convenience:
With email, you can compose and send messages at your convenience. There is no need for both parties to be available at the same time, unlike telephone conversations. You can send emails anytime and the recipient can access and respond to them whenever it suits them.

5. Documentation:
E-mail provides a written record of communication, which can be useful for future reference or documentation purposes. This is particularly beneficial in professional settings where important discussions or agreements need to be recorded and easily retrievable.

6. Attachments:
One of the key advantages of email is the ability to send attachments. Whether it's documents, images, or multimedia files, you can easily share files with others through email. This is particularly useful for sharing important documents, presentations, or large files that may be too cumbersome to send through other means.

In conclusion, while options like telephone, fax, and letter have their own merits, email emerges as the easiest means of communication due to its accessibility, speed, cost-effectiveness, convenience, documentation capabilities, and the ability to send attachments.