Explanation:

- The sum of the first 78 natural numbers can be calculated using the formula for the sum of an arithmetic series: \( \text{Sum} = \frac{n(n + 1)}{2} \), where \( n \) is the last number of the sequence.

- For 78, this becomes \( \frac{78 \times 79}{2} = 3081 \).

- Now, let's test divisibility by each option:

- Option 1: 79

- 3081 is divisible by 79 (3081 divided by 79 equals 39).

- Correct Answer is 79.

- Option 2: 61

- 3081 is not divisible by 61.

- Option 3: 29

- 3081 is not divisible by 29.

- Option 4: 30

- 3081 is not divisible by 30.

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