A boy begins at P and walks $3.0\,\text{m}$ due north from P to Q, then goes $4.0\,\text{m}$ due east from Q to R. What is the shortest distance he must now travel to make his overall displacement zero?
- A$3.0\,\text{m}$
- B$4.0\,\text{m}$
- C$5.0\,\text{m}$
- D$7.0\,\text{m}$