Which of the following lines of HTML code will insert an image into a webpage?

The line of HTML code that correctly inserts an image into a webpage is the one that uses the <img> tag. This tag is specifically designed for displaying images on a webpage. The src attribute within the <img> tag is vital, as it specifies the source URL of the image file that should be displayed.

In this case, the structure of the statement is accurate because it follows the proper HTML syntax required to embed an image, ensuring that when implemented in a web browser, the image will appear as intended. The other options provided do not use valid HTML tags for image insertion; thus, they would not function as intended in a web development context.