By what means can one optimize the performance of a mission-critical application within a business project? In what ways is it possible to reduce costs and increase efficiency?

the answer is 2 because a candidate key should define all the attributes of any relation. in second depandancy (a,d) is not defining all the attributes of the relation(a,b,c,d,e)

2 not determine all attributes while 1 and 3 do

2 - A canidate key is a subset of a superkey (hence, why it is also called a "minimal superkey"). A superkey is capable of uniquely identifying all rows. #2 is the only one that doesn't list all of the attributes. Hence, it can't be a superkey . I implement this on my website

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