Which one of the following exhibits double fertilization? 

During pollination, pollen grains are transferred to the female receptive organ called the stigma where one viable pollen germinates and develops a pollen tube that grows down the style of the flower. The pollen tube carries two male gametes from the pollen which eventually enter the ovule within the ovary. 

One male gamete fuses with the egg cell to form a zygote in a process known as syngamy, while the second male gamete fuses with the two polar nuclei in the central cell to form the triploid primary endosperm nucleus or PEN and the process is known triple fusion. 

Since fertilisation occurs twice, the phenomenon is referred to as double fertilisation.

Angiosperms (flowering plants) are characterised by double fertilisation in the plant kingdom. E.g. maize, coconut, etc.