Maryland and northwest territory were connected through the a.) national railroad b.) national skyway c.)national canal d.) national road

The right answer is the D: National Road.

The National Road was the first highway in the United States funded with the support of the federal government. It was constructed between 1811 and 1834 with the goal of connecting the East with the Ohio River, making possible the transportation to the West of thousands of settlers. It started to be built in 1811 in Cumberland, Maryland, hence the name Cumberland Road that is also used in order to refer to it. It soon became a very popular and traveled road, although in the last decades of the 19th century it was partially replaced with the railroad.  

This road is known today in many places as Route 40.

c

explanation: