Meaning: 'Occurred' means that something happened or took place, referring to the migrations to the islands.

Wrong options:

• incurred: 'Incurred' means to become subject to something unwelcome or unpleasant, which does not fit the context of migrations happening.
• concurred: 'Concurred' means to agree or have the same opinion, which is irrelevant in the context of migrations.
• spurred: 'Spurred' means to encourage or prompt, which does not convey the idea of migrations happening.

Correct answer: drifted

Explanation: The word 'drifted' is appropriate here as it suggests a passive movement, which fits the context of whether humans arrived by accident. It is grammatically correct and aligns with the idea of being carried by ocean currents.

Meaning: 'Drifted' means to be carried slowly by a current of air or water, indicating an unintentional arrival.

Wrong options:

• airlifted: 'Airlifted' refers to transporting something by aircraft, which is not relevant to ancient maritime navigation.
• sifted: 'Sifted' means to separate or sort through, which does not apply to the context of movement across the ocean.
• shifted: 'Shifted' means to move from one place to another, but it does not convey the passive nature of the journey implied by 'drifted.'

Correct answer: shed

Explanation: The word 'shed' fits grammatically and contextually as it refers to the act of casting off or revealing information. It aligns with the phrase 'shed light on,' which means to clarify or provide insight into something.

Meaning: 'Shed' in this context means to provide or reveal, particularly in terms of information or understanding.

Wrong options:

• drop: 'Drop' means to let something fall, which does not fit the context of providing insight.
• place: 'Place' refers to a location or position, which does not convey the idea of revealing information.
• embrace: 'Embrace' means to accept or support, which is not relevant to the context of providing clarity.

Correct answer: simulated

Explanation: The word 'simulated' is appropriate as it indicates that the buoys are mimicking or replicating the conditions of a wayward raft. This fits grammatically and contextually within the sentence structure.

Meaning: 'Simulated' means to imitate or replicate, particularly in a way that mimics real conditions.

Wrong options:

• insulated: 'Insulated' means to protect from heat, cold, or sound, which does not fit the context of tracking a raft.
• stimulated: 'Stimulated' means to encourage or provoke a response, which is not relevant to the function of the buoys in this context.
• regulated: 'Regulated' means to control or maintain the rate or speed of a process, which does not apply to the idea of simulating a raft's journey.