A corporate employee's inbox starts with 100 unread emails and receives 15 new ones each day. This is modeled by the function $N(t) = 100 + 15t$, where $N$ is the total number of unread emails and $t$ is the number of days. Based on this model, which of the following correctly identifies the variables?

An office administrator uses the function $N(t) = 100 + 15t$ to estimate the backlog of unread messages in a shared inbox, where $t$ represents the number of business days and $N$ represents the total number of unread emails. Match each variable to its correct role in this mathematical model.

In the function $N(t) = 100 + 15t$, which models the total number of unread emails ($N$) in a corporate inbox after $t$ days, the variable $N$ is considered the independent variable.

Variable Identification for Email Backlog Model

An administrative assistant is monitoring a department's email backlog, starting with 100 unread emails and accumulating 15 more each day. This scenario is modeled by the function $N(t) = 100 + 15t$, where $N$ is the total number of unread emails and $t$ is the time elapsed in days. Because the number of days dictates the total email count, the elapsed time $t$ represents the ____ variable.