Determine the points where the function $h$ has local maxima or minima given $h^{\prime }\left(x\right)=(x-15)(x+21)(x-13)$.

• A. Local minimum at: $x=-21$ $x = 15$Local maxima at: $x=13$ and $x = 15$
• B. Local minima at: $x=13$ and $x = 15$Local maximum at: $x=-21$
• C. Local minima at: $x = -21$ and $x = 15$Local maximum at: $x=13$
• D. Local minimum at: $x=13$Local maxima at: $x = -21$ and $x = 15$

Answer: (C)