Explanation:

Here's how to solve the problem:

- In 2018, the ratio of steel to iron is 3:2.

- In 2020, the ratio of steel to iron is 1:1.

- The ratio of steel imported in 2018 to that in 2020 is 4:3.

Let's assume the quantity of steel in 2018 was 4x and in 2020 it was 3x.

Using the steel ratios, the quantity of iron imported in 2018 would be $\frac{4x}{3}\times \frac{2}{3}$ = $\frac{8x}{9}$, and in 2020 it's the same as steel in 2020 (1:1 ratio), or 3x.

So the ratio of iron from 2018 to 2020 is $\frac{8x}{9}:3x$, simplifying to 8:9.

- Option 1: 11:12 - Not matching the simplified ratio.

- Option 2: 7:5 - Not matching the simplified ratio.

- Option 3: 8:9 - Correct ratio.

- Option 4: 7:9 - Not matching the simplified ratio.

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