Answer: d) B & C
Explanation: Variable substitution is the method through which the command substitution is done for the other form of command and regains its value or meaning.
This value substitution is done with the help of double quotes("...") which are inverted as well when a new form of command is to be introduced and it is known as back quotes. Other given options are incorrect because it is not determined in single quotes.Thus the correct option is option (d).
Connections, allow separate systems to communicate directly with each other, eliminating the need for manual entry into multiple systems. They do not entirely eliminate information redundancy, but they do ensure information consistency among multiple systems.
Viruses spread when the software or documents they get attached to are transferred from one computer to another using a network, a disk, file sharing methods, or through infected e-mail attachments. Some viruses use different stealth strategies to avoid their detection from anti-virus software.
