Find the largest open intervals on which the function is concave upward or concave downward, and find the location of any points of inflection.

$f(x)=4x^3+7x^2-6x+5$

Select the correct choice below and fill in the answer boxes to complete your choice.

$($Type your answer in interval notation. Use a comma to separate answers as needed. Use integers or fractions for any numbers in the expression.$)$

A$.$ The function is concave upward on and concave downward on

B$.$ The function is concave upward on $.$ There are no intervals on which the function is concave downward.

C$.$ The function is concave downward on $.$ There are no intervals on which the function is concave upward.