This is most analogous. Just as the historian watches craftspeople today making pottery to speculate about the making of similar pottery in the past, the author used observations of modern sand dunes to speculate about the features of sand dunes in the past.

This doesn’t involve observing something in one context in order to support a belief about the thing in a different context. Asking working-age people about their employment status is directly relevant to the rate of unemployment. There’s no need to analogize from one context to another. It also doesn’t involve studying the present to infer something about the past.

This doesn’t involve observing something in one context in order to support a belief about the thing in a different context. It involves reading what people wrote to speculate about what they thought. But (C) doesn’t involve a shift to a different context. For example, it doesn’t say that the historian uses what she learns from the ancient manuscripts to speculate about what a different group of people must have thought. It also doesn’t involve studying the present to infer something about the past.

This involves studying the past to develop a theory about the future. But the passage involved studying the present to speculate about the past.

This doesn’t involve observing something in one context in order to support a belief about the thing in a different context. It also doesn’t involve studying the present to infer something about the past. Rather, it involves studying the past to reveal something about the past.