An independent variable is a variable which change is not affected by that of another variable. By process of elimination you can take out B and C. An independent variable can also change so that takes out A. That leaves D.
Acid rain, or acid deposition, is a broad term that includes any form of precipitation with acidic components, such as sulfuric or nitric acid that fall to the ground from the atmosphere in wet or dry forms. This can include rain, snow, fog, hail or even dust that is acidic.
Building walls and houses, fire pits, construction materials, decoration etc...
Je dirais que c'est vrai car le gabbro est une roche à grain grossier et il est igné, ce qui signifie qu'il a été formé par le refroidissement et la solidification du magma ou de la lave. Je n'en suis pas tout à fait sûr, mais c'est mon avis, et je m'excuse pour toute erreur de grammaire car le français n'est pas ma langue maternelle.
Removing the oxygen in water
