Grass Flowers Lack Petals and Sepals

Grass flowers lack petals and sepals. Which of the following statements is TRUE?

A) They are pollinated by flies, which don't require showy, scented petals.
B) These flowers are pollinated at night, so they don't benefit from showy petals or sepals.
C) They are incomplete flowers lacking one or more floral parts.
D) They are imperfect flowers lacking stamen or carpals.