The grass is wet because it rained last night. This seems the simplest and most elegant expression of the meaning. I am always suspicious of reason (s) and why being next to each other.

The answer to this question clearly explains the standard rule that when you have multiple quoted paragraphs, each new paragraph starts with an opening quotation mark, but only the final quoted par Why is used here as an interjection. According to merriam-webster: €used to express mild surprise, hesitation, approval, disapproval, or impatience