Part A: Students from high school B is the most consistent, because their standard deviation (σ=28.2) is the smaller than that of A and C. Smaller standard deviation means less variations among the values, or more consistence.
Part B: High school A has the highest average attendance, because it has higher mean (82) than B and C. Mean is mathematically the same as average, total number of days attended by all students divided by the number of students.