The correct option is
A Papilionaceae
Fabaceae or Papilionaceae is a large and economically important family of flowering plants.
Vexillary aestivation is seen in members of Fabaceae. In vexillary aestivation, the outermost posterior petal is large which is known as the vexillum or standard, two lateral petals are known as the wings or alae, and the two anterior and innermost petals are united to form a boat-shaped structure known as the keel or carina. Hence, vexillum is found in Papilionaceae.So, the correct answer is 'Papilionaceae'.