Early pencil leads were made of solid graphite mined in Cumberland, in Britain.
Information
Comparison early pencil lead: solid graphite (mined in Cumberland) modern pencil lead: powdered graphite
Causality (result of / thus) Research sponsored modern methods by govt of France in 1790 >> of powdered graph
France at war no access to with Britain >> Cumberland graphite
Evaluate
The second sentence contains two causal ideas that could potentially chain together.
1. France and Britain go to war 2. Thus, the French can't make solid graphite pencils using Cumberland's graphite. 3. Thus, the French government sponsors research into an alternative and comes up with powdered graphite. 4. Those methods are used today.
So we could potentially say that modern methods of manufacturing pencil leads trace back to the 1790s, when France and Britain were at war.
Goal
Look for whatever answer we can best support.