An End User Is Seeing Long Web Page Load Times

An end user is seeing long web page load times on the internal business application that they are trying to view. The user is seeing this issue across multiple web browsers, and other users encounter the same issue. Which action should the system administrator take to start looking for the cause of this issue?

A) Check to make sure Nginx is running.
B) Check for response times in Nginx logs.
C) Check to make sure the web API response is coming back in JSON.
D) Check the size of the database that the application is using.