Which of the following is an example of jargon?

Jargon refers to specialized language that is specific to a particular field or profession, making it difficult for outsiders to understand. The phrase "TCP/IP protocol" is an example of jargon because it pertains to computer networking and is commonly used in the technology industry. It consists of acronyms that represent complex concepts in that specific domain. For someone without a background in information technology, this phrase may not be easily understood, exemplifying how jargon serves as a communicative tool within specialized groups while potentially alienating those not familiar with such terminology.

The other phrases listed, while they may have idiomatic or colloquial meanings, are not specific to any particular field and are more commonly understood in everyday conversation. Thus, the use of "TCP/IP protocol" distinctly highlights jargon due to its specificity and technical nature.