If the national day of a country was celebrated on the 4th Saturday of a month, then find the date of celebration in that month, when the first day of the month is Tuesday.

The first day of the month is Tuesday.

To find the first Saturday, count the days from Tuesday:

• Day 1: Tuesday
• Day 2: Wednesday
• Day 3: Thursday
• Day 4: Friday
• Day 5: Saturday

The 1st Saturday is on the 5th of the month.

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Since Saturdays occur every 7 days, the Saturdays of the month are:

1st Saturday: Day 5

2nd Saturday: Day $5 + 7 = 12$

3rd Saturday: Day $12 + 7 = 19$

4th Saturday: Day $19 + 7 = 26$

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Therefore, the national day is celebrated on the 26th of the month.

The answer is Option 3: 26th.