Which one is not one of the four requirements for cognitive systems?

Which of the following was discovered in the piedmont region of north carolina in 1799?

An object weighs 40n in air , weighs 20n when submerged jn water and 30n submerged in a liquid of unknown density .what is the density of the liquid?

When pay is made public, people evaluate how equitable their pay is in light of the pay other people are receiving. the problem in this case is that dwight and guillermo have found out that others are getting paid more than they do for the same work. what are they likely to do under these circumstances