Final answer:
The number located to the right of -1 on the horizontal number line is -2 2/3.
Step-by-step explanation:
In the context of the question, we are given a horizontal number line. The number line extends infinitely in both directions, with positive numbers to the right of zero and negative numbers to the left of zero.
Since -1 is to the left of zero, the number to the right of -1 on the horizontal number line would be a positive number. In the given options, the only positive number is -2 2/3 (option c), so that is the correct answer.