During Pollination, Multiple Pollen Grains Are Delivered to the Stigma

During pollination, multiple pollen grains are delivered to the stigma. Which of the following phenotype traits provides the greatest selective advantage for successful fertilization?

A) high pollen tube growth rate and ability to detect chemicals from synergid cells surrounding the egg
B) high rate of mitosis in the growing pollen tube
C) elaborate and striking UV "nectary guides" on the petals to guide an insect to the stigma
D) Pollen grain with large generative cell to provide enough cytoplasm for pollen tube growth