The most appropriate word to fill in the blank is; c) respectful.
In English language, an adjective is one of the parts of speech and it can be defined as a word that qualifies or describes a noun in a sentence. Some examples of an adjective are big, small, happy, tall, short, fat, rambunctious, respectful, etc.
Respectful simply means to be characterized by respect, politeness or showing deference.
In this context, respectful is an adjective that qualifies or describes the clothe (a noun) she is wearing. Thus, we can infer that her clothes command respect and shows deference.
In conclusion, she always wear respectful clothes even though she's not rich.