State the type of measurement in each of the following statements:
a. I rode my bicycle $15 \mathrm{~km}$ today.
b. My dog weighs $12 \mathrm{~kg}$.
c. It is hot today. It is $30{ }^{\circ} \mathrm{C}$.
d. I added $2 \mathrm{~L}$ of water to my fish tank.