Which of the following Westgard rules may be considered a "warning" rule?

The most common symptom of myocardial infarction is __________

a. bloodshot eyes b. heavy breathing c. chest pain d. excessive thirst

The force that occurs between two surfaces moving against each other, which increases when the moving surfaces are rougher and decreases when they are smoother, is ____________

Fill in the blank(s) with the appropriate word(s).