Final answer:
The best activity for Ms. Simeone to assess whether her first-grade students are attending to the left-to-right directionality of the number system is to have them write two-digit numerals in ascending order.
Step-by-step explanation:
The best activity for Ms. Simeone to assess whether her first-grade students are attending to the left-to-right directionality of the number system would be to have them write two-digit numerals in ascending order (option C). This activity will require the students to understand and apply the correct sequencing of numbers from left to right. By writing the numerals in ascending order, the students will need to start with the smallest two-digit number and proceed to the larger ones.