The Answer Is.....
C- Hijrah.
Answer:
The opal is the National Gemstone of Australia. The opal is almost exclusively located within Cretaceous sedimentary rocks of the Great Artesian Basin, Intense weathering resulted in extensive silicification at relatively shallow levels within the Tertiary regolith.
The free rider problem<span> is a market failure that occurs when people take advantage of being able to use a common resource, or collective good, without paying for it, as is the case when citizens of a country utilize public goods without paying their fair share in taxes.</span>
