A glass cube of length 21 cm has a small air bubble trapped inside. When viewed normally from one face, its apparent distance is 8 cm. When viewed normally from the opposite face, its apparent distance is 6 cm. The refractive index of the glass and the actual distance of the air bubble from the first surface respectively are:

The refractive index $n$ of the glass and the actual distance $d_1$ of the air bubble from the first face must be determined. The total thickness of the glass cube is $L = 21\text{ cm}$.

When viewed normally from the first face, the apparent distance is $8\text{ cm}$, giving the relation for apparent depth: $n = \frac{d_1}{8}$, so $d_1 = 8n$.

When viewed from the opposite face, the apparent distance is $6\text{ cm}$, and the actual distance from that face is $d_2 = 21 - d_1$. Using the apparent depth formula again: $n = \frac{21 - d_1}{6}$, so $21 - d_1 = 6n$.

Substituting $d_1 = 8n$ into this equation yields $21 - 8n = 6n$, resulting in $21 = 14n$ and $n = \frac{3}{2} = 1.5$.

Then $d_1 = 8 \times 1.5 = 12\text{ cm}$.

The correct option is A: $1.5, 12\text{ cm}$.