Hill Corporation Ltd$.,$ an Internet service provider, has been providing networking solutions to Riverdale High School for over a year. However, recently the administration at Riverdale high School has been complaining of an unstable connection. You are employed by Hill Corporation for the purpose of inspecting the issue at hand. What would be your first check point to ensure that there are no network issues from the service provider's end?

a$.$ The entrance facility

b$.$ The individual distribution frame $($IDF$)$

c$.$ The data room

d$.$ The main distribution frame $($MDF$)$