a) The answer is on page 209.

b) The total amount of mono-nitrogen oxides (NOx), which originates mainly from the operation of small trucks and vans (11.319 tonnes) and large trucks (14.534 tonnes), is calculated by adding these amounts together (25.853 = 11.319 + 14.534).

c) Compared to 2016, a decrease of NOx emission emitted results from the increase in the percentage of vehicles complying with Euro 6 and the impact of the Euro norm on the weighted average conversion factor for NOx.