Which of the following is a correct statement concerning the NAT function of a router for connecting to the internet?
a) This function allows a fast display of the contents of a Web server whose IP address was stored in a cache when it was accessed previously.
b) This function detects specific bit patterns from IP packets during transmission.
c) This function allows only IP packets to be sent to specific terminals to pass.
d) This function performs two-way conversion between the private IP address and the global IP address.