Which of the following statements is correct with regard to root canal instrumentation?

Reamers or files are placed in the canal to its determined length, rotated one complete turn, removed, cleaned and the process repeated.

If the root canal is curved the instrument must be precurved before insertion.

Reamers only are used in curved canals

Use of a reamer must be followed by use of a corresponding file

Files are more effective than reamers for removing necrotic debris from root canals