I think its option d. hope this helps :)
It is a book about botany/environment.
Hint: Model words are helping words used to describe the state of the given circumstance. These words can be used to express emotions, requests, exasperation, permission and so on. Eg: May I help you? Will you send it to me by evening? Shall I help you with the groceries? The word, will, is used to represent any kind of actions that is definite to take place in the future, while, would, and is often used for requests, permissions and invitations.
Answer: <em><u>Would</u></em> you open the window please?
Explanation: "Would" is a modal verb most commonly used to create conditional verb forms. It also serves as the past form of the modal verb "will." Additionally, "would" can indicate repetition in the past.
