Quantity A: 5 × (area of △ABC).
Quantity B: area of the circle.
Triangle ABC is inscribed in a circle with center O.

This choice suggests that the area of triangle ABC, multiplied by 5, is greater than the area of the circle. However, without knowing the dimensions of triangle ABC or the radius of the circle, we cannot ascertain if this is true. The triangle could be small relative to the circle or large enough to exceed the circle's area, making this option inconclusive.

This option indicates that the area of the circle is greater than the area of triangle ABC multiplied by 5. Similar to the previous choice, without specific measurements, we cannot determine whether the circle's area exceeds that of the triangle. The triangle could potentially occupy a significant portion of the circle, thus making this statement not universally valid.

This choice posits that the area of triangle ABC multiplied by 5 is equal to the area of the circle. However, this equality can only hold true under very specific conditions that are not provided in the question. Therefore, we cannot conclude that the two areas are equal without additional information.