Internet access by transmitting digital data over the wires of a local telephone network is provided by
A. Leased line
B. Digital subscriber line
C. Digital signal line
D. None of the mentioned

Hint: In this question, we first see the definition of a leased line that is used as a private telecommunication link for connecting two places using symmetric data, fixed-bandwidth, and is dedicated connection. Then we the definition of DSL that is Digital Subscriber Line (DSL) is a medium for communication that is used to carry the internet through the telecommunication line made up of copper wire.

Complete step-by-step answer:
A leased-line is used as a private telecommunication link for connecting two places using symmetric data, fixed-bandwidth, and is a dedicated connection. One place may be an office and the other place maybe another office or a data center that is connected to a wide area network or the internet. These lines are used to connect PCs and servers, link to the Internet, allow staff to connect to their work PCs from home, and carry phone calls.

Digital Subscriber Line (DSL) is a medium for communication that is used to carry the internet through the telecommunication line or telephone network made up of copper wire. Besides cable internet, DSL is also one of the most popular methods used by Internet service providers (ISPs) to provide broadband internet connection.
It maintains a very high internet speed for transferring data.

The digital subscriber line (DSL) is able to achieve both internet and telephone facilities because it uses DSL filters or splitters. Here splitter is used to split the frequency and check that these frequencies don't get interrupted.

The internet service provided by the Digital subscriber line (DSL) only operates up to a limited distance and is not available in those areas where the telephone network is unable to support the DSL. Therefore the DSL service is not accessible everywhere. This connection is more efficient and faster for receiving data than it is for sending data using the internet.

A digital signal line is used to transmit and receive digital signals using a specific communication link.
Hence from the definition, it is clear that DSL is the method used to access the data by transmitting the digital data using a wire on a local telephone network. Therefore option B is correct.

Note: For these types of questions we need to be clear with different terms like Asymmetric digital subscriber line (ADSL), Digital subscriber line(DSL), Very-high-bit-rate digital subscriber line (VDSL), public switched telephone network (PSTN), leased-line, and metro Ethernet.