Which of the following series of events is listed in proper sequence? a. work begun on erie canal; work begun on baltimore and ohio railroad; work begun on national road b. the telegraph was put into commercial operation; work begun on national road; work begun on baltimore and ohio railroad c. work begun on baltimore and ohio railroad; work begun on national road; work begun on erie canal d. work begun on national road; robert fulton's steamboat, clermont navigated the hudson river; work begun on baltimore and ohio railroad.