Answer;
D. where two plates collide
Explanation;
-Subduction zones are plate tectonic boundaries where two plates converge, and one plate is thrust beneath the other. This process results in geohazards, such as earthquakes and volcanoes.
-Subduction zone volcanism occurs where two plates are converging on one another. One plate containing oceanic lithosphere descends beneath the adjacent plate, thus consuming the oceanic lithosphere into the earth's mantle. This on-going process is called subduction.
Its an electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell.
B. so light can shine through it from below.
The frequency of the radio station is

For radio waves (which are electromagnetic waves), the relationship between frequency f and wavelength

is

where c is the speed of light. Substituting the frequency of the radio station, we find the wavelength:
It will travel slowest through gases.