Physics

To minimise parallax error, the observer should place the object :


ANSWER

as near to the scale of the ruler as possible and the eye must be directly above the scale


SOLUTION
$$Answer:-$$ A
There are three simple ways of reducing parallax error in that case: 
1. Attach a straight object (like a ruler or straightened paperclip) to the thing you're measuring the displacement of, it should stick out of the object perpendicularly to the scale you're measuring the displacement on. 
2. Make sure that object is as close to your scale as possible, but not touching. 
3. Put your eyes level with the object, and as close to it as you safely can.
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