Final answer:
During the first year of implementing the interim assessment program, the most important concern for the principal in the district should be the limited access that teachers have to their students' interim assessments.
Step-by-step explanation:
The most important concern that a principal in the district should consider during the first year of implementing the interim assessment program is B. Teachers had only very limited access to their students' interim assessments before the assessments were administered. This is because teachers need to have access to the assessments in order to analyze the areas of strengths and weaknesses of their students and adjust their instruction accordingly. Limited access to the assessments can limit the effectiveness of the program.