Only B undermines it. All the rest support it.
Could you show how B undermines the argument? I am still not much clear!
The conclusion reads After all, a person’s chance of being involved in a mishap increases in proportion to the number of times that person drives.
According to the conclusion the more you drive the greater the risk of being involved in an accident. What if we can prove that this isn't the case? B certainly does that by showing that
People who drive infrequently are less likely to follow rules for safe driving than are people who drive frequently. Therefore by not following safe rules they stand a higher chance of being involved in an accident.