Answer to Question 1
Concrete operational thinking is based on systematic, logical thought processes. Children in the concrete operational period are able to use reversible and flexible processes. They understand that an object that changes in one dimension will compensate in another dimension. They are also able to think about more than one dimension of a problem at a time. They can understand class inclusion problems because of this, with an object being able to belong to more than one class at a time. They are less egocentric in their thinking as well.
Answer to Question 2
A