Explanation:

Correct Option 1: BDAC

The correct order of the sentences to form a meaningful and coherent paragraph is:

B → D → A → C

Here's how the paragraph flows:

B. During the spring of 1717, the iron foundries in a remote district were often visited by a thin, middle-aged man with a notebook.
D. He would weigh out two pounds of iron, have them heated till they were red-hot and then weigh them again.
A. He repeated the experiment, increasing the amount until he had weighed up to a thousand pounds.
C. Three cauldrons were next prepared under his directions.