Answer:
b. two-sided
Step-by-step explanation:
If an element contains text or another element, it is marked using a two-sided tag set in which an opening tag and a closing tag enclose the element content.
For example, <p>it is very important to "check" the expiration date of goods before buying them.</p>. In this scenario, the <p> represents the opening tag while the </p> represents the closing tag in HTML programming.