The contraction of the heart is initiated by a small cluster of cardiac muscle cells called what?

1. b vitamins2. vitamin k3. vitamin d4. examples are walnuts, seeds, tofu5.  total fat, saturated fat, trans fat, cholesterol, sodium, total carbohydrate, dietary fiber, sugars, protein, vitamin a, vitamin c, calcium, and iron.6. 11257. they have to contain reliable information8. less than 10%  9. i didnt read the course so im not surehope that : p

Ithink it's traditional