Bebras 2019 - Level 2 Question 14

The wizard Bibrax places 49 coins on a table. Bibrax closes his eyes and asks a beaver to flip any one coin. When he opens his eyes, he will tell the beaver which coin was flipped. The secret is: “The number of star-side-up coins in each row and each column was initially even.”



Editable transcription of the displayed coins:

| Row | A | B | C | D | E | F | G |
|---|---|---|---|---|---|---|---|
| 1 | Blank | Star | Blank | Star | Blank | Star | Star |
| 2 | Star | Blank | Blank | Blank | Star | Star | Star |
| 3 | Star | Blank | Star | Star | Blank | Star | Blank |
| 4 | Star | Blank | Blank | Blank | Blank | Star | Blank |
| 5 | Blank | Star | Blank | Star | Star | Star | Blank |
| 6 | Star | Blank | Star | Star | Blank | Star | Star |
| 7 | Blank | Blank | Blank | Star | Blank | Blank | Star |

Which coin has the beaver flipped in the figure?