Monopoly - are there substitute products if there's only one company?


CFA 2017 Level 1 Schweser Notes Book 2 - Economics, page 44 under “Key Concepts, LOS 15.” they say:

  • "Monopoly is characterized by:
    • A single firm that comprises the whole market.
    • Very high barriers to entry into or exit from the industry.
    • _ Advertising used to compete with substitute products. _
    • Significant pricing power. "

My questions is, how can there be substitute products if there’s only one company to sell the product/service?


Imperfect substitutes.