MCQOPTIONS
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| 1. |
Astronomers recently discovered the youngest known neutron star named Swift J1818.0-1607. It is how many years old? |
| A. | 160 |
| B. | 200 |
| C. | 240 |
| D. | 280 |
| E. | 320 |
| Answer» D. 280 | |