When writing an ionic compound formula, a "molecular" form is used. The formula is made with allowance for ion charges.
For example,
Ca²⁺ and NO₃⁻ ⇒ Ca(NO₃)₂
Al³⁺ and SO₄²⁻ ⇒ Al₂(SO₄)₃
Answer:
it depends where you live really... lol
C. all the other choices are positive impacts to the environment unlike C
Putting them in that oder can be absolutely wrong becaus they are not in the same group of the periodic table