My brain has never grasped the concept of main idea and topic sentences. I know what they are and i understand that but in my head, if someone is asking me to find the main idea or topic sentence of a paragraph i think to myself "the whole paragraph. Thats why paragraphs exist right? To break up topics and ideas." Anyways, i have an assignment which i will post below

"As you read this final paragraph, again consider the clues that imply the main idea.

I was in the National Forest with my camera. The day was crisp and the leaves were bright with fall colors. When I spotted the white-tailed buck, I froze. He was less than 15 yards from where I was standing. The wind must have been right, because he kept on grazing on the mossy ground. I lifted my camera very slowly. Carefully, holding my breath, I lifted the camera to my eye. Turning the focus ring, I framed the deer’s head. Just as I was ready to press the shutter release, the buck raised his head. He was looking my way with wide eyes. Click—I took the picture. An instant later the deer bounded away into the forest. He took off, but I had the shot. Today, the framed photo of that buck hangs above our fireplace.

What is the main idea of this piece? What are the clues? What does the author imply? If you think it is about a photo that was very important to the writer, you’re right. How does the last line help you make that inference?"

Im having trouble completing it. I understand the question but i just dont know how to get to the answer. If anyone can help me I'll appreciate it. Thank you.