The diagram shows a clinical thermometer. What feature in the diagram indicates that this is a sensitive thermometer?
- AIt has a range of $7^\circ\text{C}$.
- BThere are equal distances between each $^\circ\text{C}$ mark on the scale.
- CThere is a constriction in the tube at X.
- DThere is a large distance between each $^\circ\text{C}$ mark on the scale.