Answer
• Improving the environmental performances
• Developing Green Mining technology
Explanation
The effect to the environment caused by opal mining are; impact on soils and geology, clearing of native vegetation disrupting flora and fauna, change in land use and effects of air quality.
Opal mining is currently examining environmental impacts and adopting measures that mitigate the impacts making the process less destructive to the environment.
With the current commitment to sustainability, opal companies are investing funds for Green Mining as a positive way to impact the environment before and after mining.
It’s going to be both answer A and B but if you can only answer one then it’s going to be B
Answer:

Explanation:
When the unpolarized light passes through the first polarizer, only the component of the light parallel to the axis of the polarizer passes through.
Therefore, after the first polarizer, the intensity of light passing through it is halved, so the intensity after the first polarizer is:

Then, the light passes through the second polarizer. In this case, the intensity of the light passing through the 2nd polarizer is given by Malus' law:

where
is the angle between the axes of the two polarizer
Here we have

So the intensity after the 2nd polarizer is

And substituting the expression for I1, we find:

Because the specimen is very small with a light microscope
In order from shortest to longest frequency, the electromagnetic waves can be ranked :
1. X-rays
2. Ultraviolet
3. Infrared
4. Microwave
X-rays has the shortest frequency which ranges between 30 petahertz to 30 exahertz. X-rays have the smallest wavelengths at 0.01-10 nanometers. Its energy ranges between 100eV to 100keV.