The correct answer is (a) <bdi>
To explain I would say: <bdi> element is known as bidirectional isolation. It isolates a span of text that might be formatted in different direction from other text outside it. This element is useful at the time of embedding text with an unknown directionality from database like inside text with a fixed directionality. <br> is used for giving a break-line in text. <b> is used for making the text bold. To override the current text direction <bdo> element is used.