When the Mongols came to power in China in the 1200s, they made travel along the Silk Road safer than it had been in centuries. One result was that

the answer is d trust me

a. theta waves. this is because the person is in a light sleep which means the brain waves would show these kind of waves.

they usually pass federal laws

and sometimes in the elections of the president

it would be a. that is the only one i could think of