Concept:A microscope uses two convex lenses to magnify tiny objects for detailed observation.
Explanation:A convex lens converges light and can enlarge an image.
In a compound microscope, the objective lens (convex) forms a real, inverted, and magnified first image of the object.
The eyepiece lens (also convex) then magnifies this first image further, allowing the eye to see fine details.
Using two convex lenses in this way produces much higher overall magnification than a single lens alone.
A concave lens diverges light and reduces image size, so it cannot provide the required magnification.
A convex mirror forms only virtual images, which are not suitable for further magnification by an eyepiece.
Thus, a microscope must be a combination of two convex lenses.
Answer:Two convex lenses (Option A).