Blood type and personality has been a challenging issue to study scientifically, with some large surveys showing statistically significant associations. However, the relationship between blood type and personality remains uncertain. More than half of Japanese people believe there is a legitimate relationship between blood type and personality traits.

1. A

2. B

3. AB

4. O

5. The relationship between blood type and personality has long been
one of the more challenging issues of scientific studies. Several
large-scale surveys were conducted to address the issue, and some
of them had shown statistically significant associations. Presently,
more than half of Japanese people feel that the relationship is
legitimate.