The correct option is
A One lobed anther
A monothecous stamen has only one-lobed anther with two pollen chambers, also called bisporangiate. it is seen in Malvaceae. A dithecous stamen has two lobes of anthers with four pollen chambers, also called tetrasporangiate. Sterile anthers are seen in staminode stamens, as seen in
Cassia.
Hence, the correct answer is 'One lobed anther'