The correct answer is The page number only
Since you've already mentioned who the author is, you don't have to mention him again. The book title would only be added if you're using multiple sources from the same author. If only one, then the page number only.
C because cloud is part of nature and they are always moving and growing so it changes, nature is always changing
<em>“The inflated style itself is a kind of euphemism. A mass of Latin words falls upon the facts like soft snow, blurring the outline and covering up all the details. The great enemy of clear language is insincerity. When there is a gap between one’s real and one’s declared aims, one turns as it were instinctively to long words and exhausted idioms, like a cuttlefish spurting out ink. In our age there is no such thing as ‘keeping out of politics.’ All issues are political issues, and politics itself is a mass of lies, evasions, folly, hatred, and schizophrenia. When the general atmosphere is bad, language must suffer. I should expect to find — this is a guess which I have not sufficient knowledge to verify — that the German, Russian and Italian languages have all deteriorated in the last ten or fifteen years, as a result of dictatorship.”</em>
This is an example of a cause and effect relationship.
