How do the boldface headings develop the ideas in this article? they show which subtopics are most important. they introduce the topic of each section. they provide a brief timeline of edison's visit. they provide links between the ideas in different sections.

Read the sentences. the lowest point in antarctica appears to be the bentley subglacial trench, which is 8,200 feet below sea level. lower points may exist. which choice correctly uses the subordinating conjunction “although” to combine the sentences? the lowest point in antarctica appears to be the bentley subglacial trench, which is 8,200 feet below sea level, although lower points may exist. the lowest point in antarctica appears to be the bentley subglacial trench, which is 8,200 feet below sea level. although lower points may exist. the lowest point in antarctica appears to be the bentley subglacial trench, which is 8,200 feet below sea level although, lower points may exist. the lowest point in antarctica appears to be the bentley subglacial trench, which is 8,200 feet below sea level; although lower points may exist.