Lucy is a smart girl.

Answer: Option D

Smart : (of a person) clean, tidy, and well dressed.
Casual : relaxed and unconcerned.
Indecent : not conforming with generally accepted standards of behaviour, especially in relation to sexual matters.
Active : engaging or ready to engage in physically energetic pursuits.
Scruffy : shabby and untidy or dirty.

Antonym of Smart is Scruffy