I believe the answer is true. Hope this helps.
Answer:
CaO + SO 3 → CaSO. 4
This is an acid-base reaction (neutralization): CaO is a base, SO 3 is an acid.
A compound is where two or more elements have chemically bonded, and a mixture is where there are two or more elements are grouped together, but they are not chemically bonded.
An example of a mixture would be salt dissolved in water, and an example of a compound would be water (which is made up of 2 Hydrogen and 1 Oxygen bonded together)
tl;dr: I would go with B, basically.
These rocks were either roasted or exposed to severe weathering
