In Heuristics for the Travel Distance Calculation, how system calculate Depth-first search? Please choose the correct answer.

In Heuristics for the Travel Distance Calculation, how system calculate Depth-first search? Please choose the correct answer.
A . The system attempts to find a route between the specified nodes of a network in the average time possible. Here, the search runs in the direction of start node to end node. The search finishes when the last complete route is found.
B . The system attempts to find a route between the specified nodes of a network in the average time possible. Here, the search runs in the direction of start node to end node. The search finishes when the first complete route is found.
C . The system attempts to find a route between the specified nodes of a network in the shortest time possible. Here, the search runs in the direction of start node to end node. The search finishes when the first complete route is found.
D . The system attempts to find a route between the specified nodes of a network in the longest time possible. Here, the search runs in the direction of start node to end node. The search finishes when the first complete route is found.

Answer: C