Which CSS function can be used to make an element's size responsive to the viewport height?

The function that allows an element's size to be responsive to the viewport height is the "vh()" function. This function is designed to work specifically with viewport dimensions, where 1vh represents 1% of the viewport height. As the height of the user's browser window changes, an element styled with a size defined in vh units will adjust to maintain a relative size based on the new height, ensuring that the layout remains flexible and visually appealing across different screen sizes and orientations.

Using "calc()" is intended for performing calculations when you need to combine different units or values, but it does not inherently define responsiveness to viewport height. "min()" is used to return the smallest value among its parameters, which may not relate directly to viewport height. "rem()" relates to the root element's font size and is used for font sizing and spacing rather than adapting to viewport dimensions.