At which depth below earth’s surface is the boundary between earth’s outer core and stiffer mantle
located?
(1) 700 km (3) 2900 km
(2) 2000 km (4) 5100 km

The depth below Earth's surface at which the boundary between Earth's outer core and stiffer mantle is located is 3. 2900 kilometers. This is the location where the outer core that covers our planet ends and meets its mantle that can be found within the Earth and is stiffer than the very center of the planet which is made of iron.

Ansradar; im guessing here; good luck : )