Answer:
The correct answer is letter "C": an increase in the bargaining power of suppliers of a critical input.
Explanation:
Porter's Five (5) Forces is an analysis scheme created by Harvard School Professor Michael E. Porter (born in 1947). The ultimate goal of this analysis is to help managers set their expectations because profitability decreases as competition increases. Three of the five forces relate to industry (horizontal) participants - the threat of substitutes established rivals, and new entrants. The other two relate to the vertical participants - the bargaining of suppliers and consumers.
In the case, as airline fuel suppliers are consolidating, this would represent the bargaining of suppliers factor in Porter's theory. They could joint to decide quantities supplied or even prices.