A beam of light travels through three different media: A, B, and C. Their refractive indices are 1.33, 1.65, and 1.46, respectively. In which medium does light travel fastest?

• Medium A: $n_A = 1.33$
• Medium B: $n_B = 1.65$
• Medium C: $n_C = 1.46$

Comparing the values: $1.33 < 1.46 < 1.65$.
The lowest refractive index is 1.33, which corresponds to Medium A.

Since Medium A has the lowest refractive index, light will travel fastest in Medium A.

The correct option is (A).
The medium in which the light will travel fastest is $\boxed{\text{A}}$.