Meaning: 'Potential' means the possibility or capability for something to occur or develop in the future.

Wrong options:

• shingle: Shingle refers to a type of roofing material or a small flat piece of wood, which does not relate to the context of planets forming.
• cymbal: Cymbal is a musical instrument, which is irrelevant in the context of discussing planets and their formation.
• tittle: Tittle refers to a small stroke or point in writing, particularly in letters, and does not fit the context of planetary formation.

Correct answer: discovery

Explanation: The word 'discovery' is a noun that fits grammatically as it indicates the act of finding or learning something new. In this context, it refers to the announcement made by Meyer regarding new findings about stars, making it contextually appropriate.

Meaning: 'Discovery' means the act of finding or uncovering something that was previously unknown.

Wrong options:

• ethology: Ethology is the study of animal behavior, which does not relate to the context of astronomical findings.
• battery: Battery refers to a device that stores energy or a series of connected electrical components, which is irrelevant in this context.
• somebody: Somebody is an indefinite pronoun referring to an unspecified person, which does not fit the context of announcing a scientific finding.

Correct answer: candidates

Explanation: The word 'candidates' fits grammatically as a plural noun indicating entities that are suitable or eligible for something. In this context, it refers to stars that are suitable for the development of rocky planets, aligning well with the sentence's meaning.

Meaning: 'Candidates' means individuals or entities that are considered for a particular role or purpose, in this case, stars that could support rocky planet formation.

Wrong options:

• ambulates: Ambulates is a verb meaning to walk or move about, which does not fit the context of discussing stars and their suitability for planet formation.
• tabulates: Tabulates is a verb meaning to arrange data in a table, which is irrelevant in this context.
• pomegranates: Pomegranates are a type of fruit and do not relate to the context of stars or planetary development.

Correct answer: presence

Explanation: The word 'presence' fits grammatically as a noun indicating the state of being present or existing. In this context, it refers to the existence of larger rocky bodies colliding, which is essential to the overall meaning of the sentence.

Meaning: 'Presence' means the state of being present or existing in a particular place or situation.

Wrong options:

• prisons: Prisons are facilities for confinement, which does not relate to the context of astronomical observations.
• metals: Metals are elements or materials, which do not fit the context of discussing the existence of colliding bodies in space.
• envisions: Envisions is a verb meaning to imagine or visualize, which does not fit grammatically or contextually in this sentence.

Correct answer: formation

Explanation: The word 'formation' fits grammatically as a noun indicating the process of being formed or created. In this context, it refers to the process that led to the creation of terrestrial planets, making it contextually appropriate.

Meaning: 'Formation' means the action of forming or the process of being formed, particularly in a scientific context.

Wrong options:

• vocation: Vocation refers to a person's occupation or profession, which does not relate to the context of planetary development.
• innervation: Innervation refers to the supply of nerves to a body part, which is irrelevant in the context of planetary formation.
• operation: Operation refers to the act of functioning or working, which does not fit the context of discussing the creation of planets.