Why were the gold prospectors called 49ers?
it was the cost of coming across the country.
it took 49 days to get clear claim to lands.
it was the price of an ounce of gold.
it was the year of the great gold rush.

The answer to your question will be D.

Proof from wiki:

"forty-niners" (referring to 1849).

s the president shall be commander in chief of the army and navy of the united states, and of the militia of the several states, when called into the actual service of the united states; he may require the opinion, in writing, of the principal officer in each of the executive departments. sooo yeahhh

explanation:

the process of industrialization is called a revolution because