Right choice is (b) <basefont>
Best explanation: <applet> embeds java applet in web document. <basefont> is obsolete HTML element. It sets default font face, size, and color for other elements which are descended from its parent element. Instead of using this element we can use font, font-size, font-family and color to change font configuration for an element. <acronym> element which has been removed from HTML5 indicates sequence of characters. <big> element increase the font size.