Final Answer:
The proportion of the slave population in the fifteen slave states is best represented by 2/3. This indicates that approximately two-thirds of the population in those states were slaves, So, the correct answer is D) 2/3.
Step-by-step explanation:
The proportion of the slave population in the fifteen slave states is better represented by option D) 2/3. This implies that approximately two-thirds of the population in these states were slaves.
In detail, considering the historical context of slavery in the United States, particularly in the Southern states, a significant portion of the population consisted of slaves. Option D aligns with the demographic distribution during the period in question.
Therefore, the correct option is D) 2/3.