The type of causal reasoning involved when explaining a single situation in terms of many possible causes is known as explanation.

idiographic explanation

Explanation:

Type of causal reasoning is an idiographic explanation  

we know that there are 2 types of  approach for understanding the social life

and here idiographic approach use for understanding single or individual type case or event but a nomothetic approach that is used for understanding large scale social pattern

so here also cause of the single situation is exhaustively examined  

so correct answer is an idiographic explanation

the right answer is a

answer; the edward snowden leaks of nsa classified material;