Discuss the validity and effect of each of the following situations:
a. A, B, and C, manufacturers of radios, orally agree that due to the disastrous, cutthroat competition in the market, they will establish a reasonable price to charge their purchasers.
b. A, B, C, and D, newspaper publishers, agree not to charge their customers more than $0.30 per newspaper.
c. A, a distiller of liquor, and B, A's retail distributor, agree that B should charge a price of $5 per bottle.