Explanation:

- A 'Link' is a single unit of a 'Chain'. When multiple links are connected, they form a chain.

- A 'Bead' is a single unit used to make things like a 'Necklace'.

- Option 1: 'Sea' is unrelated to 'Bead'. Beads aren't inherently linked to the sea.

- Option 2: 'Peart' is not a common word related to beads or jewelry.

- Option 3: 'Jewellery' is a broad category that includes beads, but doesn't directly serve as the singular form related to a bead like a necklace does.

- Option 4: 'Necklace' is correct because a necklace is made up of or can be made up of beads.