Who claimed that behavior is controlled by environmental consequences?

How are fraternal twins different from identical twins?

a) Fraternal twins develop from one egg; identical twins develop from two eggs. b) Fraternal twins are monozygotic; identical twins are dizygotic. c) Fraternal twins have all the same genes; identical twins do not have all the same genes. d) Differences between identical twins are due to the environment; differences between fraternal twins may be due to either environment or genes.

The most commonly used descriptive statistics for a set of numerical scores are the mean and the ____

a. range b. standard deviation c. mode d. median