Seven places connected by roads - distance D to F

We must trace a continuous path from D to F using only the explicitly listed valid roads: AB, AC, CD, DE, BF, EG, FG. Start at D. The only road connecting to D that progresses toward the rest of the map is CD. Path step 1: D \rightarrow C (Road CD). Distance = 6 km (since C is 6 km north of D). Path step 2: C \rightarrow A (Road AC). Distance = 10 km (A is 10 km west of C). Path step 3: A \rightarrow B (Road AB). Distance = 6 km (A is 6 km south of B). Path step 4: B \rightarrow F (Road BF). Distance = 9 km (F is 9 km west of B). Total distance = ⟨MATH⟩6 + 10 + 6 + 9 = 31⟨/MATH⟩ km.

Answer: (c).