Object inside focal length for virtual magnification

Steps:

• Apply lens formula: 1/f = 1/v - 1/u, where u is negative for real objects; if |u| < f, v is negative (virtual image on object side).
• Virtual erect magnified image forms when object is within focal length of converging lens.
• Evaluate instruments: camera and projector use real inverted images (|u| > f); enlarger similar for projection; magnifier places object inside f for enlargement.
• Select magnifying glass as it requires |u| < f for virtual image viewed directly.

Why B is correct:

• Magnifying glass (simple microscope) positions object within focal length to produce virtual, upright, enlarged image per lens formula.

Why the others are wrong:

• A: Camera places object beyond focal length for real inverted image on film.
• C: Photographic enlarger uses object (negative) beyond focal length to project real enlarged image.
• D: Projector positions slide beyond focal length for real inverted image on screen.

Final answer: B