When the pollen grain is mature it contains two cells, the vegetative cell and generative cell. The vegetative cell
a. Is bigger
b. Spindle shaped
c. Has abundant food reserve
d. Has large irregularly shaped nucleus

The correct option is C a, c and d

Pollen grain
Pollen grain is a haploid structure that represents the male gametophyte because the male gametes are formed from them.
Development of male gametophyte
In anther of an angiosperm, the microspores undergoes mitotic division and produces two daughter cells namely generative cell and vegetative cell.
Generative cell
Generative cell is a small spindle shaped cell with dense cytoplasm and nucleus. It floats freely in the cytoplasm of the vegetative cell. It undergoes mitotic division to give rise to the two male gametes.
Vegetative cell
Vegetative cell is a large cell with an irregular nucleus and abundant food reserve.
Pictorial representation of pollen grain

Final answer
(b) a, c and d