An idea most likely to represent "common knowledge" if

Answer with Explanation

Common knowledge is to know about the general information about anything which is widely known or easily verified. It is nothing unusual, instead, it is the most general knowledge or awareness about a certain statement or evidence which would reliably be accepted by the average educated reader without having to look up. General knowledge can be said as Pyramids are one of the seven wonders of the world and English is the most common language used worldwide.

An idea can be considered as common knowledge

When all involved in the research or study are aware of the fact and on the same front also know that fact is common and is known to everyone. Also a common knowledge is not cited anywhere and is believed to be easily acceptable. Some examples of "common knowledge are -

a) There are 12 months in a year

b) Obama was the president of America