Which HTML element is correctly found in the head block of a web page?

The head block of an HTML document is designated for metadata and resources that are not displayed directly on the webpage but are essential for proper functioning and styling. The <style> element is used within the head section to embed CSS directly within an HTML document, allowing developers to define styles that will apply to the page's content.

In this scenario, the <style> tag contains a CSS rule targeting an h1 element, specifying that the text color should be red. This demonstrates the role of the <style> element in controlling the presentation of elements within the body of the document, which is appropriate and expected within the head section.

In contrast, the other options do not belong in the head section: the header element is meant to create content that appears on the page, while the DOCTYPE declaration is used at the very start of an HTML document to specify the version of HTML. The <video> tag is also a content element that is used to embed video content directly in the body of the document, not in the head. Thus, the presence of the <style> tag inside the head block is the only accurate statement regarding elements typically found in that section of an HTML document.