Answer is: b) 9,042 L.
Ideal gas law: p·V = n·R·T.
p is the pressure of the gas.
V is the volume of the gas.
n is amount of substance.
R is universal gas constant.
T is temperature.
T₁ = 15°C = 288 K.
V₁ = 10,5 L.
T₂ = -25°C = 248 K.
V₂ = ?
V₁/T₁ = V₂/T₂
V₂ = 10,5 L · 248 K ÷ 288 K
V₂ = 9,042 L.