The little girl in a red dress cautiously danced a waltz.
The adverb(s) and/or adverb phrase(s) in the sentence is/are .

(A) in a red dress only
(B) cautiously only
(C) both in a red dress and cautiously

Cautiously.

Explanation:

Cautiously is an adverb (base adjective cautious with -ly ending) modifying 'danced'  (telling how she danced).

"In a red dress" is a prepositional phrase. Some prepositional phrases can be adverb phrases, but in this sentence this prepositional phrase is an adjective phrase. It helps describe and identify the noun, 'girl.'

sentences vary by structure as well as by function. there are compound, complex, and compound-complex sentences.

simple sentence

i like to read.

a simple sentence has one independent clause.

compound sentence

i like to read, and i also like to write.

a compound sentence includes more than one independent clause, connected by a coordinating conjunction (and, but, for, nor, or, so, or yet).

complex sentence

i prefer to read books that are bestsellers.

a complex sentence includes one independent clause and one or more dependent clauses. (a dependent clause is one that cannot stand alone.) types of dependent clauses include relative clauses (i kicked the boy who pinched me), adverb clauses (i am going home now because i have a curfew), and noun clauses (i don't know what to do next).

compound-complex sentence

although i prefer to read current bestsellers, i do like to read old agatha christie mysteries, and i also like some 20th-century science fiction.

compound-complex sentences take a bunch of clauses (multiple independent clauses, and one or more dependent clauses) and toss them together like a salad. although these sentences take practice to write in a grammatically correct fashion, they can hold a tremendous amount of meaning, and are common in academic writing.