3) Formal language should avoid using which element?

A: slang
B: varied sentences
C: facts
D: strong word choice

C: facts

The element that formal language should avoid using is A: slang.

To determine which element a formal language should avoid using, let's analyze each option:

A: Slang - Formal language should avoid using slang, as it is considered casual and not appropriate for formal communication.

B: Varied sentences - Varied sentences are not something to be avoided in formal language. It is important to use a mix of sentence structures to maintain interest and flow in the writing.

C: Facts - Facts are a crucial element of formal language. In formal writing or speech, it is important to present accurate and reliable information.

D: Strong word choice - Strong word choice can be subjective. However, in formal language, the focus is more on precise and appropriate word choice rather than "strong" words. The use of overly emotional or dramatic language may not be suitable for formal communication.

Therefore, the element that formal language should avoid using is A: slang.