Verification of truth: A camera necessarily has which component? Select the part without which the device cannot function as a camera.

Introduction / Context:
This question seeks an essential component of a camera—something fundamentally required for image formation in any camera design (film, digital, phone, pinhole-equivalent optic).

Given Data / Assumptions:

• We consider “lens” broadly as the optical element (including compound lenses or functionally equivalent aperture systems for focusing an image).
• Non-essential accessories (flash, reels) and outcomes (photograph) should not be mistaken for required components.

Concept / Approach:
Image formation requires directing and focusing light from the scene onto a sensor/film plane. Modern cameras (phone, DSLR, mirrorless) use lenses; film reels are obsolete for digital cameras; flashes are optional; a “photograph” is a product, not a component.

Step-by-Step Solution:

Verification / Alternative check:
Even simple pinhole cameras implement an optical system; in common usage, “lens” covers the focusing apparatus required.

Why Other Options Are Wrong:

• Reels: not universal.
• Flash: accessory.
• Photograph: output.
• None of these: incorrect because the lens is essential.

Common Pitfalls:
Confusing historical features (reels) or accessories (flash) with core optics.

Final Answer:
Lens