What do economies aim to achieve in tackling the economic problem of scarcity? A. equal balance between public and private sectors
B. equal reward for equal effort
C. increased competition in the use of resources
D. optimum allocation of finite resource

What was piaget's explanation as to why preschool-age children in the preoperational stage make errors on tasks requiring conservation? a) preschool children's tendency toward centration prevents them from focusing on other relevant features of a situation b) preschool children have not yet developed numerical understanding; therefore, different amounts are meaningless c) preschool children's neural-visual network is not fully matured d) preschool children have not lived long enough and accrued enough experience to know the difference between quantities