Why does the velocity of P-waves decrease at the mantle-outer Core boundary? a. The outer core solid iron
b. The outer core is liquid
c. The outer core is more dense
d. The outer core is a gas

The outer core is more dense

radiative zone

explanation    

radiative zone is the layer of the sun which energy is transferred away from the core by radiation. although, the core is the only part of the sun that produces an appreciable amount of heat through fusion. in fact, 99% of the energy produced by the sun takes place within 24% of the sun's radius.