The correct answer is: $10.14\text{ US fl oz (approx.)}$
Explanation
We convert using the US fluid ounce definition: $1\text{ US fl oz} = 29.5735295625\text{ mL}$, so multiply mL by the factor $1/29.5735295625 \approx 0.0338140226$.
Steps:
- Multiply: $$300\text{ mL}\times 0.0338140226\frac{\text{US fl oz}}{\text{mL}}=10.14420678\text{ US fl oz}$$
- Round to a sensible precision: $$\approx10.14\text{ US fl oz}$$
If you meant imperial (UK) fluid ounces instead: $$300\text{ mL}\div28.4130625\frac{\text{mL}}{\text{imp fl oz}}\approx10.56\text{ imp fl oz}$$