Early pencil leads were made of solid graphite minted in Cumberland,

The correct answer choice (B) contains a couple subtle modifiers that are essential to our analysis...



Notice that source is modified by both accessible and appropriate to meet France's need for pencils. This means that France's government may have known of numerous sources of solid graphite, but if those sources were inaccessible and/or otherwise inappropriate to meet France's need for pencils, then France would have been left in need of an alternative. For example, France's government certainly knew about the source of solid graphite in Cumberland, but this source was not accessible because of the war with England. France's government may have known about a source of solid graphite buried under the Atlantic Ocean, but if that source were not accessible, France would have been out of luck.

Similarly, France's government may have known about other sources of solid graphite that were not appropriate to meet France's need for pencils (ie for economic or practical reasons). For example, perhaps France could have imported solid graphite from another country, but doing so would have made pencils unaffordable.

To summarize, did France's government know about other sources of solid graphite besides the one in Cumberland? Perhaps... but if any of those sources were accessible and appropriate to meet France's need for pencils, there may not have been a need to develop the "modern methods of manufacturing pencil leads from powdered graphite".

Choice B might not seem correct if you don't pay attention to those key modifiers ("accessible" and "appropriate to meet France's need for pencils"). This is a valuable lesson to remember when analyzing CR questions. The passage, question stem, and answer choices might contain a few tiny words/modifiers that entirely change the meaning. Unless you are paying close attention, you might overlook those words, causing a misunderstanding.