How did railroads help define the era and benefit the nation? They united the country by making tariffs profitable for each region: North, South, and West.

They helped create one integrated economy, moving raw materials from farms in the North to factories in the South.

They were used to ship goods and crops across the nation and helped achieve unprecedented growth.

They strengthened democracy in the United States by making election results known in a timelier manner.

Step-by-step explanation:

it could be C

false

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d. millimeters per hour.

step-by-step explanation:

we are given that,

carlo used a rain gauge to measure the amount of water his lawn is receiving from the sprinklers.

since, according to the options, we see that,

water cannot be measured by 'miles per hour', 'meters per second' and 'grams per seconds'.

we get that, the water can be measured by 'millimeters per hour'.

hence, the appropriate rate for describing the amount of water is 'millimeters per hour'.