Which is the most appropriate statement?

a. The next point to address is the basic two dimensions of measuring risk. That is, as well as defining the nature of the risk, we need also to think about the extent to which the risk has already materialized.

b. The next point to address is the basic two dimensions of measuring risk. That is, as well as defining the impact of the risk, we need also to think about the extent to which the risk is likely to materialize.

c. The next point to address is the basic two dimensions of measuring risk. That is, as well as defining the impact of the risk, we need also to think about the extent to which the risk has already materialized.

d. The next point to address is the basic two dimensions of measuring risk. That is, as well as defining the certainty of the risk, we need also to think about the extent to which the risk is likely to materialize.