A Identify the exact numbers.
2.54 cm (the number of centimeters in exactly 1 in)
4 choices (the number of choices in this list)
56.00 s (a time measured by a stopwatch)
3 lbs (the weight of an object measured on a scale)

the answer is (2.54cm in an inch, and 4 number of choices in this question)

Explanation:

An exact number is not rounded, and cannot be changed such as placing a different item on the scale it would change.

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.