Meaning: In this context, 'root' means the underlying cause or source of something, specifically the reason behind a dog's behavior problems.

Wrong options:

• goal: 'Goal' refers to an aim or desired outcome, which does not fit as it suggests a target rather than a cause.
• tip: 'Tip' implies a piece of advice or suggestion, which is not suitable here as it does not denote a cause of behavior issues.
• guide: 'Guide' suggests a direction or assistance, which does not align with the concept of identifying the cause of behavior.

Correct answer: inherently

Explanation: The word 'inherently' is appropriate as it indicates that dogs are not bad by nature, fitting the context of the sentence that discusses their behavior.

Meaning: 'Inherently' means something that is a fundamental characteristic or essential quality, suggesting that dogs do not possess badness as a natural trait.

Wrong options:

• recently: 'Recently' refers to a time frame, which does not apply to the nature of dogs' behavior.
• effectively: 'Effectively' means in a successful manner, which does not relate to the inherent nature of dogs.
• externally: 'Externally' refers to outside factors, which does not fit the context of discussing the intrinsic nature of dogs.

Correct answer: communicate

Explanation: The word 'communicate' is the correct form of the verb needed here, fitting grammatically as it aligns with the subject 'they' and the context of expressing needs.

Meaning: 'Communicate' means to convey or express thoughts, feelings, or needs, which is essential for understanding dogs' requirements.

Wrong options:

• have communicated: 'Have communicated' is in the present perfect tense, which is not suitable here as it does not match the simple present context.
• communicates: 'Communicates' is singular and does not agree with the plural subject 'they'.
• communicating: 'Communicating' is a gerund and does not fit grammatically in this sentence structure.

Correct answer: builds

Explanation: The word 'builds' is the correct verb form that indicates the action Alice takes to establish trust with the dogs, fitting the context of her training method.

Meaning: 'Builds' means to create or develop something over time, in this case, trust between Alice and the dogs.

Wrong options:

• convinces: 'Convinces' implies persuading someone, which does not accurately describe the process of establishing trust.
• claims: 'Claims' suggests stating something as a fact, which does not fit the context of developing a relationship with dogs.
• reveals: 'Reveals' means to make something known, which does not align with the action of fostering trust.

Correct answer: key

Explanation: The word 'key' is appropriate as it signifies something essential or crucial, aligning with the idea that understanding is vital for unlocking a dog's potential.

Meaning: 'Key' refers to something that is essential or critical for achieving a particular outcome, in this case, fostering good relationships with dogs.

Wrong options:

• service: 'Service' refers to the action of helping or doing work for someone, which does not fit the context of unlocking potential.
• point: 'Point' suggests a specific detail or argument, which does not convey the idea of something essential.
• source: 'Source' refers to the origin of something, which does not align with the concept of being crucial or essential.