What CSS property controls the text size of an element?

The CSS property that controls the text size of an element is "font-size." This property allows developers to specify how large or small the text will appear on a webpage. It can accept various values, including absolute units like pixels (px) or relative units like ems (em) or percentages (%), providing flexibility in how text is scaled in relation to other elements.

For example, setting "font-size: 16px;" will display the text at a size of 16 pixels, while "font-size: 1.5em;" will scale the text size based on the size of its parent element. Understanding "font-size" is essential for creating responsive web designs that enhance readability across different devices and screen sizes.

The other choices do not represent CSS properties that control text size. "font-style" relates to the style of the font (like italic or normal), "text-size" is not a valid CSS property, and "text-font" also does not exist in CSS standards. Thus, "font-size" is the correct choice as it directly pertains to adjusting the size of the text.