I think that the answer is C.
An identical twin I think
Aluminium, an adjuvant.
MF59 (squalene oil), an adjuvant.
Thiomersal, also called Thimerosal.
Answer:
Chemical weathering
Explanation:
Caves are formed by the dissolution of limestone. Rainwater picks up carbon dioxide from the air and as it percolates through the soil, which turns into a weak acid. This slowly dissolves out the limestone along the joints, bedding planes and fractures, some of which become enlarged enough to form caves.
Chemical weathering involves the decomposition of rocks due to chemical reactions between minerals such as calcite with water and gases in the atmosphere (e.g. carbon dioxide and sulphur dioxide). The solution of soluble minerals is particularly important in limestone landscapes.
Solutional caves or karst caves are the most frequently occurring caves. Such caves form in rock that is soluble; most occur in limestone, but they can also form in other rocks including chalk, dolomite, marble, salt, and gypsum.
Essentially, water reacts with carbon-dioxide to form carbonic acid. It then seeps slowly through the roof of the cave, depositing calcium carbonate, which hardens and builds up over time to form a stalactite.
