With repeated use of a drug, more of the drug is necessary to achieve the same effects. This demonstrates the development of

a. tolerance

Samantha is very optimistic and trusting. These characteristics are most likely to result from issues at which stage of Samantha's development?

a) Oral b) Anal c) Phallic d) Genital

When a child can simultaneously manipulate two dimensions cognitively, such as circumference and thickness, sothat s/he understands that a change in one dimension is compensated for by a change in the other, s/he understands 

A. reversibility. B. reciprocity C. identity. D. metacognition.