Correct option is : (b) helobial type
Helobial type of endosperms are found mostly in monocots. Here the first division of primary endosperm is followed by the formation of wall forming two chambers. Further divisions in both chambers are free nuclear division.
In nuclear endosperm, primary endosperm nucleus cell divides by free nuclear divisions, which are not followed by the cell wall formation. In mosaic endosperm, the tissue of endosperm is not homogeneous. Mature endosperm with any degree of irregularity and unevenness in its surface is called ruminate endosperm.