By age four, most children understand conservation

Xhao has devoted hours helping and working with Ming so that he understands his calculus homework. Such behavior exemplifies the Chinese concept of romantic love known as

a. yuan. b. gan qing. c. shiu-shiu. d. karma.

Biglan et al. (1996) studied whether store clerks in eight Oregon towns were willing to sell tobacco products to minors. They measured clerk behavior repeatedly over time, implemented a positive reinforcement intervention at different times in different towns, and usually found a drop in willingness to sell after implementing this intervention. What research methodology did they use?

a. multiple baseline design. b. interrupted time-series design. c. nonequivalent comparison group design. d. both "a" and "b"