To keep your files in order, the filing rules must be learned.
1. properly constructed sentence
2. lacks parallel parts
3. fragment
4. misplaced part
5. dangler

1). Properly constructed sentence.

Explanation:

As per the question, the given sentence reflects a 'properly constructed sentence' as it is both syntactically and semantically appropriate. The first part of the sentence prior to comma correctly displays the purpose i.e. 'to keep your files in order' while the latter part of the sentence mirrors how the purpose can be solved by 'learning the filing rules.' Thus, it conveys the meaning of the sentence most adequately without any confusion since it is appropriately structured and punctuated. Therefore, option A is the correct answer.

the answer should be a)directions.

the answer is   c the cold war