3 (a) That's wrong. The facts of the case study do not indicate that anybody has suffered purely economic harm or loss. B has lost four weeks of income but this is not a purely economic loss - it flows directly from B's physical injuries. Such losses are recoverable as damages flowing from the physical injuries.
Harm is properly said to be purely economic when it happens without any physical injury to the plaintiff or their property. Compensation can be claimed for purely economic harm caused by physical acts but special rules are applied to limit the extent of liability. A plaintiff is more likely to succeed if they are one of a finite or identifiable group of persons likely to be harmed; and if they were unable to protect themselves from the harm caused by the defendant's acts; and if the defendant was aware of this vulnerability and the extent of the harm and the degree of risk involved.