Match antennas to their typical directivity levels: (A) Horn antenna, (B) Parabolic antenna, (C) Lens antenna — with: (1) high directivity, (2) very high directivity, (3) moderate directivity.

Introduction / Context:
Antenna directivity measures how concentrated the radiated power is in a particular direction. Recognizing typical directivity ranges for common microwave antennas is essential in RF system design.

Given Data / Assumptions:

• Antennas: Horn, Parabolic reflector, Dielectric lens.
• Directivity labels: moderate, high, very high.

Concept / Approach:
A horn provides aperture matching and moderate gain; a parabolic reflector focuses energy tightly for very high directivity; a lens antenna increases directivity by phase-front shaping, generally between horn and large parabolic dishes.

Step-by-Step Solution:

Verification / Alternative check:
Rule of thumb: Directivity ∝ effective aperture area. Parabolic reflectors typically achieve the highest for a given size; horns are simpler waveguide flares; lenses add focusing power without reflectors.

Why Other Options Are Wrong:

• A-1, B-2, C-3: Overstates horn and understates lens relative positions.
• A-3, B-1, C-2: Swaps lens and parabolic levels.
• A-1, B-3, C-2: Misorders all three against typical practice.

Common Pitfalls:

• Equating gain one-for-one with size without considering aperture efficiency.
• Assuming horns inherently provide very high directivity regardless of dimensions.

Final Answer:
A-3, B-2, C-1