Meaning: Cacophony means a loud, unpleasant mixture of sounds, often used to describe a noisy environment.

Wrong options:

• euphony: Euphony refers to a pleasing or harmonious sound, which contradicts the context of overwhelming noise.
• symphony: Symphony implies a harmonious arrangement of sounds, which does not fit the chaotic nature described.
• monophony: Monophony refers to a single melodic line without harmony, which does not capture the complexity of the noise described.

Correct answer: backs

Explanation: The verb 'backs' is used here to indicate support or endorsement, which is appropriate in the context of the World Health Organization providing evidence or support for the claim about noise affecting health. It fits grammatically as a present tense verb that aligns with the subject 'the World Health Organization.'

Meaning: Backs means to support or endorse something, indicating that the World Health Organization supports the idea that noise is harmful to health.

Wrong options:

• keeps: Keeps does not fit contextually as it implies maintaining something rather than supporting a claim.
• packs: Packs suggests gathering or containing, which does not align with the context of providing support or evidence.
• backs: Backs is the correct option, while the others do not convey the intended meaning.

Correct answer: vital

Explanation: The word 'vital' indicates something that is essential or necessary, which aligns with the context of silence being an important healing process in many religions. It fits grammatically as an adjective that describes the noun 'healing process.'

Meaning: Vital means essential or necessary for life or health, emphasizing the importance of silence in healing.

Wrong options:

• functional: Functional suggests something that is practical or useful, but does not convey the essential nature of silence in healing.
• celestial: Celestial relates to the sky or outer space, which is not relevant to the context of healing processes.
• detrimental: Detrimental means causing harm, which is the opposite of what is intended in this context.

Correct answer: unravel

Explanation: The verb 'unravel' means to investigate or clarify something complex, which fits well in the context of neuroscientists and health professionals exploring the benefits of silence. It fits grammatically as a present tense verb that aligns with the subject 'a group of neuroscientists and health professionals.'

Meaning: Unravel means to investigate and clarify something that is complicated, indicating the process of discovering the benefits of silence.

Wrong options:

• retrieve: Retrieve implies getting something back, which does not fit the context of discovering or investigating benefits.
• relieve: Relieve suggests alleviating something, which does not align with the context of exploring or uncovering benefits.
• unleash: Unleash means to release or set free, which does not convey the idea of investigating or clarifying.