The speed with which a modem transmits data is called its:a. digital velocityb. dynamic ratec. modular ratingd. transfer rate

The correct answer is d. transfer rate.

Step by step explanation:

1. The question is asking for the term that describes the speed at which a modem transmits data.

2. The options given are digital velocity, dynamic rate, modular rating, and transfer rate.

3. Digital velocity, dynamic rate, and modular rating are not standard terms used to describe the speed of data transmission in a modem.

4. The transfer rate, on the other hand, is a standard term used in computing to describe the speed at which data is transferred from one location to another. In the context of a modem, it refers to the speed at which the modem can send and receive data.

5. Therefore, the correct answer is d. transfer rate.