Most people buy insurance because they

One requirement for an industry to be perfectly competitive is that

A) there are no restrictions on entry into or exit from the market. B) there are multiple restrictions on entry into or exit from the market. C) there are many firms selling different products. D) sellers and buyers have imperfect information about prices. E) the many firms sell slightly different products.

If at a given moment, no matter what the price, producers cannot change the quantity supplied, the momentary supply

A) has zero elasticity. B) has unit elasticity. C) has infinite elasticity. D) does not exist.