Explanation:

- The passage discusses the historical significance of Essaouira as a cultural and commercial hub on Morocco's Atlantic coast.

- It's important to determine what preposition best fits the context of linking "Timbuktu" with "Africa's interior."

- Option 1: in - "In" denotes location within limits or boundaries, which aligns with the idea of Timbuktu being within Africa's interior.

- Option 2: above - Typically used to indicate a higher position, which doesn't logically relate to positioning in this context.

- Option 3: over - Implies movement or extending across, which is less fitting here than "in."

- Option 4: on - Refers to a surface, position, or time, not apt for describing geographical interiors.

Answer: Option 1: in is the correct choice. It suggests Timbuktu is located "in" the interior of Africa. .