Introduction:
In today's digital era, sending emails has become an essential part of communication. With the advancement in technology, emails can now be sent through various devices such as PCs, tablets, and smartphones. This flexibility allows users to access and send emails from anywhere and at any time, making it convenient and efficient.

PC (Personal Computer):
- PCs or personal computers are the traditional devices used for email communication.
- They provide a more comprehensive and user-friendly interface for managing emails.
- Users can access their email accounts through web browsers or email client applications installed on their PCs.
- Email clients like Microsoft Outlook, Mozilla Thunderbird, or Apple Mail allow users to configure their email accounts and send/receive emails directly from their desktop.

Tablet:
- Tablets have gained popularity as portable devices that offer the functionality of a PC with the convenience of a mobile device.
- Users can access their email accounts through email client applications or web browsers installed on their tablets.
- Tablets provide a touch screen interface, making it easy to navigate and compose emails.
- With the availability of Wi-Fi or cellular data connectivity, users can send emails from their tablets while on the go.

Smartphone:
- Smartphones have revolutionized the way we communicate, including email communication.
- Smartphones offer email client applications or built-in email features that allow users to access and manage their email accounts.
- The compact size and portability of smartphones make it extremely convenient for users to send and receive emails anytime, anywhere.
- Additionally, smartphones provide various features such as push notifications, allowing users to receive instant alerts when new emails arrive.

All of the above:
- The correct answer to the question is option 'D,' which states that emails can be sent via PC, tablet, and smartphone.
- This means that regardless of the device being used, users can access their email accounts and send emails.
- Whether it's a PC, tablet, or smartphone, as long as the device is connected to the internet and has email capabilities, users can compose and send emails.

Conclusion:
In conclusion, emails can be sent via various devices such as PCs, tablets, and smartphones. The flexibility provided by these devices allows users to stay connected and communicate efficiently through emails. Whether it's at home, in the office, or on the go, individuals can conveniently access their email accounts and send emails using the device of their choice.