I'm doing microecomomics hw, but I'm stuck on these few probelams. Can anyone answer one or more of them? Thanks in advance!

1. Which of the following is not necessary for price discrimination to occur?
a.control over price by the firm
b.a downward-sloping demand curve facing the firm
c.economies of scale exist
d.the firm can easily prevent resale of the good by lower-price customers
e.the firm can easily distinguish groups with different price elasticities

2. When government regulations force a natural monopoly to produce where price equals average total cost, social welfare is
a.maximized
b.minimized
c.greater than it would be without regulation, but it is not maximized
d.less than it would be without regulation
e.exactly the same as it would be without regulation

3. Each firm has a downward-sloping demand curve for loanable funds because its
a.marginal resource cost slopes upward
b.marginal rate of return on investment curve slopes upward
c.marginal rate of return on investment curve slopes downward
d.marginal revenue product curve slopes upward
e.marginal resource cost curve slopes downward

4. The interest rate charged on a home mortgage is lower than the interest rate charged on a credit card because:
a.The administration costs are lower on mortgages
b.A home mortgage is less risky than a credit card because the home becomes collateral
c.A home mortgage is riskier than a credit card
d.The administration costs are higher on credit cards
e.The mortgage loan amount is lower than the credit on a credit card