Rock and minerals are both considered to be natural substances and this is what they have in common.
A colon suggests that there will be a list that will follow it. Using the words 'such as', 'for example', and 'including' in a sentence also directs the attention of the reader to a list. It will be redundant to use a colon after the word 'including' in a sentence.
I am thinking A because b and c don't really express period of two weeks. It comes down to a or d. When you just talk or write you will most likely use a.
