Final answer:
C) S=2f
To create an image of the same size as the object in a concave mirror, it needs to be placed at a distance of twice the focal length.
Step-by-step explanation:
To place an object in front of a concave mirror with a focal length f, such that the image is of the same size as the object, it needs to be placed at a distance equal to twice the focal length, S = 2f. This is because a concave mirror forms a virtual and magnified image when the object is placed between the mirror and its focal point. The distance between the object and the mirror affects the size of the image formed.
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