Answer:
The correct answer is letter "A": readily available substitute.
Explanation:
American Harvard School Professor Michael E. Porter (born in 1947) states there are Five Forces determining the factors that influence industry competition and profitability. Those forces are:
According to Porter, the bargaining power of suppliers is powerful when switching costs of buyers are high, when there is a small number of suppliers compared to buyers, when switching costs of suppliers are low or when substitutes are unavailable.