The petals of the flowers are usually conspicuous to attract birds for pollination.

Answer: Option A

Prominent : situated so as to catch the attention; noticeable.
Beautiful : pleasing the senses or mind aesthetically.
Colourful : having much or varied colour; bright.
Scented : having a pleasant scent.
Conspicuous : attracting notice or attention.

Synonym of Conspicuous is Prominent