Final answer:
The HTML tags mentioned are incomplete, but tags such as <strong> and <em> are used to semantically emphasize text, and <mark> highlights text visually.
Step-by-step explanation:
The HTML tags mentioned are incomplete and do not provide enough information to determine if they are used to highlight text. In HTML, the <strong> tag is commonly used to indicate that text is important and should be bolded, which does visually highlight the text to a degree. Other tags like <em> (emphasis) can italicize text, and <mark> highlights text by giving it a background color. Each HTML tag has a specific purpose and should be used according to the semantic meaning you intend to convey with the text.