The problem describes a gas expanding at constant pressure. This indicates that Charles's Law should be used.

The problem describes a gas expanding at constant pressure. This indicates that Charles's Law should be used.
Charles's Law states that for a fixed amount of gas at constant pressure, the volume is directly proportional to its absolute temperature.
The formula for Charles's Law is:

$$\frac{V_1}{T_1} = \frac{V_2}{T_2}$$

Where:
$V_1$ = initial volume
$T_1$ = initial absolute temperature
$V_2$ = final volume
$T_2$ = final absolute temperature

Given values:
Initial volume, $V_1 = 3.25 \text{ dm}^3$
Final volume, $V_2 = 9.75 \text{ dm}^3$

We need to find the ratio of the final absolute temperature to the initial absolute temperature, which is $\frac{T_2}{T_1}$.

From the formula $\frac{V_1}{T_1} = \frac{V_2}{T_2}$, we can rearrange it to find $\frac{T_2}{T_1}$:
Multiply both sides by $T_2$:

$$\frac{V_1 T_2}{T_1} = V_2$$

Divide both sides by $V_1$:

$$\frac{T_2}{T_1} = \frac{V_2}{V_1}$$

Substitute the values of $V_1$ and $V_2$ into the rearranged formula:

$$\frac{T_2}{T_1} = \frac{9.75 \text{ dm}^3}{3.25 \text{ dm}^3}$$ $$\frac{T_2}{T_1} = 3.0$$

The calculated ratio is 3.0.
The given options are:
A) 3.1
B) 5.2
C) 5.4
D) 8.5

The closest option to the calculated value of 3.0 is A) 3.1.

The final answer is $\boxed{\text{A) 3.1}}$.