Final answer:
The availability of minerals can be determined using radioactivity, magnetism, and gravity.
Step-by-step explanation:
The reading used to determine the availability of minerals is all of the above (A) radioactivity, (B) magnetism, and (C) gravity.Radioactivity can be detected using radiometric dating methods, which allow geologists to determine the age of rocks and minerals. Magnetism can be used to identify certain minerals that have magnetic properties. Gravity measurements can help detect variations in local geology and the presence of minerals.