A spacecraft's landing is cushioned by airbags. As it lands on Mars, the velocity of downward fall is 20 m/s. Immediately after impact, the velocity is 10 m/s. If the spacecraft has a mass of 7.1×10⁴ kg, what is the value of the impulse?

a. 1.2×10⁴ kg m/s

b. 2.2×10⁵ kg m/s

c. 7.1×10⁵ kg m/s

d. 3.6×10⁴ kg m/s