Classify the following events as mostly systematic or mostly unsystematic. Is the distinction clear in every case?
a. Short-term interest rates increase unexpectedly.
b. The interest rate a company pays on its short-term debt borrowing is increased by its bank.
c. Oil prices unexpectedly decline.
d. An oil tanker ruptures, creating a large oil spill.
e. A manufacturer loses a multi-million-dollar product liability suit.
f. A Supreme Court decision substantially broadens producer liability for injuries suffered by product users.