Given:

f(x) = 3x⁴-8x³-48x+25.

F’(x) = 12x³-24x²-48 = 0

F’(x) = 12(x³-2x²-4) = 0

Differentiating again, we get,

F’’(x) = 3x² – 4x = 0

x(3x – 4) = 0

x = 0 or x = 4/3

Putting the value in equation, we get,

f(x) = -39

Hence, C is the correct answer.