Explanation:

- The car travels from the 13th tree to the 34th tree, covering 21 tree gaps (34 - 13 = 21).

- This journey takes 18 seconds.

- To determine the time to travel from the 1st to the 50th tree, we calculate the total tree gaps: 49 (50 - 1 = 49).

- Using the same speed, the time taken is proportionate: \( \frac{49 \text{ gaps}}{21 \text{ gaps}} \times 18 \text{ seconds} \).

- This simplifies to approximately 42 seconds.

Option 1: 42 seconds is correct.

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