Final answer:
The arccosine of 3/4 is the angle π/3, as this is the angle on the unit circle whose cosine corresponds to 3/4.
Step-by-step explanation:
The arccosine of 3/4 is the angle whose cosine is 3/4. Since cosine values correspond to x-coordinates on the unit circle for a given angle, we can identify which angle would have a cosine value of 3/4. According to the unit circle, the angle whose cosine is 3/4 is π/3 or 60 degrees. Therefore, the correct answer is A) π/3.