Select the one-word substitute that best expresses the meaning of the phrase "a gesture expressing respect, such as a bow".

Introduction / Context:
This question focuses on one-word substitutes, a favourite topic in English vocabulary sections. The phrase describes a respectful gesture, for example a bow or similar act, and you must identify the concise term that captures this idea. Knowing such words improves both exam performance and the quality of formal writing.

Given Data / Assumptions:

- Phrase: a gesture expressing respect, such as a bow. - Options: Consensual, Obeisance, Perk, Germinate. - Only one option should match the meaning of a respectful bodily gesture.

Concept / Approach:
The noun obeisance means a movement of the body, such as a bow or curtsy, made as a sign of respect or obedience. It can also mean the act of showing great respect in general. The other options belong to different semantic fields: consensual refers to mutual agreement, perk refers to a benefit or advantage, and germinate refers to the process of a seed starting to grow. Therefore, obeisance is the only word that fits the given phrase.

Step-by-Step Solution:
Step 1: Focus on the key idea in the phrase: a gesture that expresses respect. Step 2: Consider situations such as people bowing before a leader, a deity, or an elder. That entire act is called obeisance. Step 3: Examine option B, Obeisance, and recall that it is commonly used in sentences like They made obeisance before the king. Step 4: Look at option A, Consensual, which relates to consent and mutual agreement, not to respectful gestures. Step 5: Observe that option C, Perk, describes a benefit or perquisite, often in employment contexts. Step 6: Option D, Germinate, is about seeds starting to grow, and has no link to respect or gestures. Step 7: Conclude that only option B matches the meaning of the given phrase.

Verification / Alternative check:
Create a sample sentence: The disciples bowed in obeisance to their guru. This sentence perfectly illustrates the meaning of a respectful gesture such as a bow. Replacing obeisance with consensual, perk, or germinate makes the sentence absurd, which confirms they are semantically unrelated. This is a strong indication that obeisance is the correct one-word substitute for the phrase.

Why Other Options Are Wrong:
Consensual is used in contexts where actions are done by agreement of all parties, for example consensual decision, and does not refer to physical gestures of respect. Perk describes an extra advantage or benefit, such as a company car, and is completely off topic. Germinate describes the beginning of growth of a seed or idea and does not convey respect or physical movement.

Common Pitfalls:
Students sometimes pick unfamiliar words at random, hoping that they match hidden meanings. A more reliable approach is to learn one-word substitutes with example sentences and group them by themes, such as respect, fear, movement, or speech. Recognising that obeisance belongs to the theme of respect and ceremony helps to recall it quickly in exam conditions.

Final Answer:
Obeisance is the correct one-word substitute for a gesture expressing respect, such as a bow.