Which of the following characteristics relates to the formal operational stage?
a. The Piagetian stage, extending from 2 to 7 years of age, during which the child's use of language becomes more sophisticated but the child has difficulty with the logical mental manipulation of information
b. The Piagetian stage, beginning at about age 11, marked by the ability to use abstract reasoning and to solve problems by testing hypotheses
c. The Piagetian stage, extending from 7 to 11 years of age, during which the child learns to reason logically about objects that are physically present
d. Erikson's developmental stage in which success is achieved by having a secure social attachment with a caregiver
