In a group of items: X, Y, Z, and W, the following rules apply: 1) X cannot be selected if Y is selected. 2) Z must be selected if W is selected. Which of the following combinations is valid?
In a family of four members A, B, C, and D, A is the father of B. C is the mother of B and D is the sister of B. What is the relationship between A and C?
A family consists of a grandfather, a father, a mother, and two children. The grandfather's only son is the father. The mother is the wife of the father. How many generations are there in this family?