The function given is \( a(t) = 5000(1.12)^t \), which models exponential growth, as the amount \( a \) increases over time with a growth rate of 12% per year.
In exponential growth functions, as \( t \) increases, the output \( a \) increases slowly at first (for small values of \( t \)) and then begins to increase much more rapidly as \( t \) becomes larger. This is characteristic of exponential growth, where the increase is not linear; instead, it accelerates as the base of the exponential (in this case, \( 1.12 \)) is raised to higher powers.
Therefore, the correct statement is:
As \( t \) increases, \( a \) increases slowly at first and then quickly.