Select the phrase/connector from the given three options which can be used to form a single sentence from the two sentences given below, implying the same as expressed in the statement sentence.
Climate change adaptation is especially important in developing countries. Those countries are most vulnerable to climate change.
1. As if those countries
2. Whether those countries
3. Since those countries
1
Only 1
2
Only 2
3
Only 3
4
Both 1 and 3
5
Both 3 and 2