Which of these happened because of the columbian exchange

the dominoes began to fall. the surrender at appomattox took place a week later on april 9. while it was the most significant surrender to take place during the civil war, gen. robert e. lee, the confederacy's most respected commander, surrendered only his army of northern virginia to union gen. ulysses s. grant

explanation:

the correct answer is d

a conference committee is a group of congress representatives appointed by the senate and the house to reach an agreement over a bill that had different versions in each chamber. this is due to the fact that, to pass a law. both the house and the senate must agree on the exact same content and wording of the bill to present it to the president.

what are the options?