[1] our house was once a stop on the underground railroad. [2] it was common for an enslaved person to stop there on their way to the north. [3] the underground railroad were a network of hiding places. [4] the cellar beneath our house has a secret door that was installed to trick slave catchers. [5] living in a piece of american history is pretty interesting.

- Sentence 2.

Explanation:

Pronoun antecedent agreement rules state that a pronoun must agree to its antecedent in number or else it leads to create confusion for the readers to understand it.

As per the question, sentence 2 contains a pronoun antecedent agreement error because the singular pronoun 'an enslaved person' does not agree with the plural antecedent 'their' in number. In order to rectify this pronoun antecedent agreement error, there are two ways that involve either the  conversion of the singular pronoun to plural or the plural antecedent to singular form as shown below:

'It was common for an enslaved person to stop there on his/her way to the North.'

or

'It was common for the enslaved people to stop there on their way to the North.'

the aksumite empire was an ancient kingdom located in what is now northern ethiopia from the period of 100 ad to 940 ad. its capital was the city of aksum. the kingdom established itself as one of the 4 great powers at its time, along with persia, rome, and china.

the kingdom was rich in goods like gold, iron, and salt. it established strong commercial ties with the regions governed by rome, egypt, and persia (arabia). aksum was a key location in this commercial network. trade was also facilitated with the introduction of the aksumite currency.

answer; epigenetics;