The dot product of vectors says [tex] u \cdot v = (x_1)(x_2) + (y_1)(y_2) [/tex], where [tex] u = x_1i + y_1j [/tex] and [tex] v = x_2i + y_2j [/tex].
Given this, the dot product for these two vectors can be solved:
[tex] (5)(-4) + (7)(3) = -20 + 21 = \boxed{1}[/tex]
Our answer is 1, or choice C.