Correct Answer : Option (D) :   Area within the downstream characteristics

Explanation : For a point A which is present in a flow field with incoming steady supersonic flow, there will be two characteristic lines passing through them. The area formed between these two characteristics in the downstream region is known as region of influence.

Correct Answer : Option (B) :   Domain of dependence

Explaination : If a point P lies at the intersection of the left and right running waves, the flow field properties at point P is dependent on the flow field information in the region upstream i.e. domain of dependence.

Correct Answer : Option (D) :   Point P

Explaination : Point P lies at the intersection of the two characteristic lines. Point A lies in the region of influence thus its flow properties depend on the properties generated due to disturbances at point P which is the intersection point.