Which of the following arrangements shows the schematic alignment of magnetic moments of antiferromagnetic substances? 

1. ↑ ↑ ↑ ↑ ↑ ↑

2. ↓ ↓ ↓ ↓ ↓ ↓

3. ↑ ↑ ↓ ↑ ↑ ↓

4. ↑ ↓ ↑ ↓ ↑ ↓