Accurate records must be kept. Modern technology must be used. Investigations must be conducted by trained scientists. Observations must be made by more than one scientist.
I am hesitating between 4 options to answer the following question, which option should I choose?
Question: What must happen in order for scientific data to be verified through repetition?
Possibilities:
- Accurate records must be kept.
- Modern technology must be used.
- Investigations must be conducted by trained scientists.
- Observations must be made by more than one scientist.

Accurate records must be kept.