Answer:
A) threats of substitute products and services
Explanation:
Porter's five forces model is used to evaluate how a company competes in a certain market. This makes it possible to analyze factors such as threat of new entrants, threat of new substitutes, competitive rivalry, bargaining power of buyers and suppliers because they affect a company's profitability. In this case, NuBreed's fertilizer is a substitute product for Tom and his family's liquid spray fertilizer. This makes it an example of a threat of substitute product and service in the Porter's five forces model.