What is the default optimal path cost?
The route S,B,G costs 2+1=3 and the route S,A,G costs 1+4=5, so the optimal path cost is 3 via S,B,G.
Which changed heuristic condition fails?
Admissibility: h(B)=10 exceeds true remaining cost 1; consistency also fails on B->G.
What does h=0 produce?
Uniform-cost search on nonnegative edges.