[a] The relations of two sub-entity sets of the same super entity set have 1- The same keys 2- The same attributes 3-The same constraints 4- The same natural joins with their super entity set 5- All of the above 6- None of the above b] The condition A B in a WHERE clause of an SQL query, where A is an attribute in relation R and B an attribute in relations S, is true 1- For all values of A and B where A B 2-For all values of A and B where A = B except when A has a NULL value 3-For all values of A and B where A = B except when B has a NULL value 4-For all values of A and B where A = B except when A and B have NULL values 5- All of the above 6- None of the above [c] The condition A ALL A in a WHERE clause of an SQL query, where s is a scalar and A an attribute in relation R, is true if 1- s is not equal to any value of A 2-s is not equal to any value of A that is not NULL 3- s NOT IN A 4-s=NOT ANY A 5- All of the above 6- None of the above [e] A tuple constraint that references an attribute A in relation R to attribute B in relation S is checked 1-When changes in R are made 2- When changes in attribute A are made 3- When changes in S are made 4- When changes in attribute B are made 5- All of the above 6- None of the above