Answer to Question 1
center
Rationale: In order for AEC to work properly, the part must be properly centered and the anatomy should cover the entire photocell to ensure correct determination of exposure termination for optimal density. Improper coverage of AEC with anatomic part could result in under or overexposure.
Answer to Question 2
grids
Rationale: Grids are designed to absorb scatter to reduce the amount of scatter affecting the image.