The setting which would allow us to observe a specimen with the highest possible magnification is the Objective 10x Ocular 10x.
Explanation:
To observe a specimen with the highest possible magnification is the magnification needed to be the maximum. To gain such a magnification, magnification power of objective and magnification power of ocular or eye lens will be required together at max being the product. Because,
Magnification of object = magnification by ocular lens x magnification by objective lens.
Thereby, among the option, when the magnification power of objective lens is 10X and that of ocular lens is 10X, together will produce a magnification of 100X.
