Attractive antennas that pull the waves tword it.
The answer is; C
The radioisotopes in the interior of the earth are not in pure form and have many embedded impurities and are interspersed. Therefore when a neutron is released by a decaying atom, its chances of hitting another radioisotope atom (to continue the chain reaction) are lower than in a manmade nuclear reactor. This way, the radioactive chain reaction in the earth’s interior is not well sustained.
A flash flood is when to much water overflows a certain area. This is common with storms. When it rains; small bridges tend to floor. Garages, basements, and cellars can tend to flood as well from storms.
After dipping the litmus paper strips in the solutions, the answer to the question is that one is acidic because according to brad's observation on turned red and the others are basic or alkaline with the two papers turning blue.