I am not completely sure, but I think that standards of performance, or "performance goals", are used to measure productivity.
Answer:
Due to the holes in history records
Explanation:
We can never truly be certain who invented the lightbulb, so people have different arguments about it
It is answer C. They didn't understand the test and probably didn't know what they got wrong and couldn't study.
Answer:
Convex = outward, Concave = inward
Explanation:
Concave is like a cave in that it goes inward, and convex is just not concave
B: Occur naturally, have a fixed chemical composition