Choose the sentence that contains a comma splice. a) since it was chilly, i ordered some coffee at the snack bar. b) because this has been a very dry summer, the supply of reservoir water is very low. c) as i sat on a bench and drank my coffee, a seagull passed over, he relieved himself on my head. d) as i leaned over the railing of the ferry, i watched the seagulls dip down into the deep green water.

First of all, you need to know what a comma splice is. A comma splice, also known as a run-on sentence, means that two or more sentences are mixed into one large sentence but with improper punctuation. So, a comma is inserted where a period should be to separate two or more unrelated sentences.
Having this in mind, the correct answer is C. As I sat on a bench and drank my coffee, a seagull passed over, he relieved himself on my head. 
There should be a period between the words 'over' and 'he.'

things change.

The poem "Ozymandias" discusses the fate of an Egyptian ruler. When he was a pharaoh, he built fantastic works, and erected a monument to himself so that everyone who looked at all the splendour would know he was responsible, and would feel intimidated by his power. However, the speaker tells us that after many centuries, none of the splendour remains. Everything is now destroyed and buried by the sand. This shows how even the most amazing projects and the most powerful rulers are eventually forgotten. The theme of the poem, therefore, is that things change.