Are usually the most significant parts of a message communicated.
tone and body language
body language and words
words and tone
words

Communication is divided into two parts; verbal and non verbal communication. The verbal communication needs words and non verbal communication needs expressions. Therefore, body language and words are usually the most significant parts of a message communicated. 

The correct answer is the second option "tone and body language".

Explanation:

When communicating a message, particularly a verbal message, both tone and body language are important.

As regards tone, they relate to verbal communication so its use is crucial to transmitting the appropriate message. When combining tone, inflection, volume, and pace of speech in the right way, you are able to sound secure and eloquent before your audience.

As regards body language, it relates to non-verbal communication and reflects what the speaker thinks, or feels when delivering a speech. That is why it is so important to have good management of gestures, hand movements, smiling, looking at the audience's eyes, etc.

many is the pronoun that is used in this sentence. many is a quantifier that determines the amount of discoveries. when we use quatifiers followed by nouns, they act as determiners, but when they are used without a noun, as it is this case, they are pronouns.