Which is used to determine earthquake risk a. changes in the color of rocks near faults b. hydrogen gas emissions near fractures c. the height of ocean waves d. strain in rocks near faults

The option (b) ''Hydrogen gas emissions near fractures'' is the correct option.

Explanation:

Hydrogen gas is highly mobile and insoluble in the earth's water. It causes the mechanical changes in the crustal rocks due to its high mobility nature.  

When it flows into the water, it reacts with water and forms hydrogen peroxide. The outflow of the charges causes electric current in the earth's crust. If it will continue emitting charges then it will cause EM pulses which will lead to the earthquake

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.