A – Correct
Obtained by process of elimination. If DfT underestimates the number of deaths and serious injuries, then this explains why their statistics are so much lower than the hospital statistics.
B – Wrong
Roads becoming safer is not relevant to discrepancies.
C – Wrong
Hospital admissions remained unchanged. If fewer people were being admitted to the hospital for minor injuries, then there would have been a decrease in hospital admissions.
D – Wrong
This would mean that there would be more serious injuries and hence, the DfT statistics would be higher than the ones given in the text.
E – Wrong
This would make DfT statistics higher than the hospital statistics.