An oxidation-reduction reaction happens when hydrogen, oxygen or halogen atoms are transferred, so in this case, your answer would be B.
Hexane is an alkon of six carbon atoms. Hence the prefix hex-, meaning six.
You'd use the temperature change equation. The specific heat of water is always 4.18J/(g °C).
Equation to use: q=mCΔT
21.8=(2.0)(4.18)(Tf-5)
21.8=(8.36)(Tf-5)
21.8/8.36=Tf-5
2.61=Tf-5
2.61+5=Tf
Tf=7.61 °C
Since you want to know how many °C it raises, you wouldn't pay attention to the last 2 steps, however if you need to know the final temp, you want to go to the last step.