When We Say That the Effectiveness of a Particular Leadership

When we say that the effectiveness of a particular leadership style is contingent upon certain factors, we mean that

A) this leadership style is effective in all circumstances.
B) this leadership style is almost never effective.
C) the leadership style causes these factors to occur.
D) the effectiveness of the leadership style depends on what these factors are.
E) the leadership style will only emerge if these factors are present.