The correct option is
D Papilionaceae
Some plants show spontaneous to and fro movements of their leaflets. Such movements are observed in many plants. They are generally driven by temperature, touch, light, humidity, chemicals, etc.
Desmodium, which is also called as Indian telegraph plant consists of two lateral leaflets and terminal leaflets.
Leaflets of
Desmodium oscillates autonomously depending upon the temperature. Such oscillations are believed to be due to rhythmic swelling and shrinking of motor cells located in the pulvinus leaflet base. This movement of leaflets is similar to telegraphic signals.
Hence, it is also called as Indian telegraph plant.
Desmodium, Indian telegraph plant belongs to family Papilionaceae as it possesses legumes, brightly colored papilionaceous flowers.
So, the correct answer is option B.