Read the following to give the correct answer
1.
| Assertion (A): | A sundial cannot be used at night. |
| Reason (R): | A sundial depends on the position of the Sun to cast a shadow. |
2.
| Assertion (A): | An hourglass can measure time accurately only when kept straight. |
| Reason (R): | If tilted, the flow of sand inside an hourglass becomes irregular. |