The correct answer is option 'B' (Lomov).

Explanation:

Introduction:
In Anton Chekhov's play "The Proposal," Natalya is portrayed as a young woman who is highly in love with Lomov.

Natalya's love for Lomov:
1. Natalya's affection: Natalya is deeply in love with Lomov, and her feelings for him are evident throughout the play.
2. Her excitement: Natalya eagerly awaits Lomov's visit and is enthusiastic about the possibility of him proposing to her.
3. Blushing and nervousness: When Lomov finally arrives, Natalya becomes visibly flustered, blushing and displaying signs of nervousness in his presence.
4. Supporting Lomov: Natalya supports Lomov's claims and praises his virtues, showcasing her admiration and love for him.
5. Emotional outbursts: Natalya's love for Lomov is further highlighted by her emotional outbursts, such as when she becomes angry at her father for opposing the marriage proposal.

Contrast with other options:
a) Oxen Meadows: There is no mention or indication that Natalya is in love with Oxen Meadows. This option can be disregarded.
c) Her dog: While Natalya might have affection for her dog, there is no evidence to suggest that she is "highly in love" with it. This option can also be disregarded.
d) All of the above: As mentioned earlier, only option 'B' (Lomov) is correct. The other options do not have any evidence to support Natalya's love for them.

Conclusion:
Based on the given information, it is clear that Natalya is highly in love with Lomov. Her excitement, affection, emotional outbursts, and support for him throughout the play demonstrate her strong feelings for him.