First look at the condition of 1. If both courses are passed, the sum of the passing ratio of the road test and the theoretical test should be 200%.
Then 70% who passed the theory test and 80% who passed the road test add up to only 150%, which means that 50% of people failed the word test. 1 means that 10% of the students failed, so 50%-20%=30% of the students only passed the single subject exam.
These 30% people are included in 70%+80%, so the proportion of students who have passed both courses is: 150%-30%= 120%, which means that 120%/2 students have passed the theoretical examination. 60% meets the question, so it's right.
The second condition puts forward that 20% of people only pass the road test, so 50% includes 20% students who pass the road test but fail the theoretical test, while 70% students fail the theoretical test, that is to say, 30% students fail the theoretical test, including those who fail both the road test and those who fail the theoretical test, so the proportion of students who fail both is 30%. Therefore, its condition and condition 1 are equivalent and conform to the problem.
So choose d in this question.