How can you differentiate between standard and protocol? write at least on example of each of these terminologies?

Both protocol and standard define set of rules used by  two or more parties to interact between themselves.
The difference is that a standard is a formalized protocol accepted by most of the parties that implement it. Standards have exact and detailed specification regarding the network and define guidelines that specify the communication between the parties, 
Examples for protocols are: hyper-text transfer protocol (HTTP), file transfer protocol (FTP) ,transmission control protocol / internet protocol (TCP/IP)...
Examples for standards: IEEE 802.3, IEEE 802.7, IEEE 802.11,..

The answer is c. wear down