Rockville Enterprises manufactures woodworking equipment and is incorporated and based in Evansville, Indiana. Its real property is all in Indiana. Rockville employs a large sales force that travels throughout the U.S. Determine whether each of the following is a protected activity in nondomiciliary states under Public Law 86-272:

a) Rockville advertises using television, radio and newspaper in Wisconsin.

b) Rockville's employees in Illinois check the credit of a potential customer.

c) Rockville maintains a booth at an industry tradeshow in Arizona for 10 days.

d) Sales representatives check the inventory of a Tennessee customer to make sure it has enough in stock and that the stock is properly displayed.

e) Rockville holds a management seminar executive retreat for corporate executives over four days in Florida.

f) Sales representatives supervise the repossession of inventory from a customer that is not making payments on time in Maine.

g) Rockville provides automobiles to Idaho and Montana sales representatives.

h) An Alabama sales representative accepts a customer deposit on a large order.

i) Colorado sales reps carry display racks and promotional material that they place in customers' retail stores without charge.