8. Normal and inferior goods Sher enjoys going to the theater to see plays, and he also enjoys going to rock concerts. The following diagram shows two of Shen's indifference curves for going to plays and concerts. With Shen's initial budget constraint (BCI), he chose to go to four concerts and six plays per month (point X). Then his budget constraint shifted to BC, and he chose to go to five concerts and three plays per month (point). 1 PLAYS BC 10 CONCERTS of the following choices, which could have shifted Sher's budget constraint from BC to BC? Check all that apply The price of theater tickets increased while his income and the price of concert tickets stayed the same His income decreased when the prices of theater and concert tickets stayed the same The prices of both theater and concert tickets increased while his income stayed the same The prices of both theater and concert tickets decreased while his income stayed the same Based on Shen's consumption of plays and concerts after his budget constraint shifted, plays are goods, y goods and concerts are