Question

the hottest layer of the earth is the
lower mantle
crust
inner core
asthenosphere

Explanation:

The Earth's layers have different temperatures. The crust is the outermost layer and relatively cool. The lower mantle is hot but not the hottest. The asthenosphere is a part of the upper mantle and not the hottest. The inner core, being the innermost layer, has extremely high temperatures due to pressure and radioactive decay.

Answer:

inner core