What is the impulse applies to the block

r=rho l/a where a is the area, l is the length and rho is resistivity so the greater the area the lesser the resistance thats why the earth pin is thicker bcos current follow the shortest path, so less resistive .

wire in brush may conduct electricity from cell to drill and vice versa electrc shock possible

current and voltage can both be different in different parts of a circuit so it matters where you place the ammeter and voltmete

a is the best answer your welcome