Answer:
Opportunity
Step-by-step explanation:
In the SWOT analysis, external events are classified as either Opportunities or Threats, while internal events are classified as either Strenghts or Weaknesses.
In this case, we find that Blockchain is a technology that is external to IBM, and that IBM has the technological capita, and know-how, to enter this market and develop its own version of Blockchain. For this reason, the growth of Blockchain technology represents an opportunity for IBM.