Systolic Blood Pressure of Randomly Selected HMO Patients Was Recorded

Multiple Choice

Systolic blood pressure of randomly selected HMO patients was recorded on a particular Wednesday, with the results shown here. An ANOVA test was performed using these data. $$\begin{array}{l}\text { Patient Age Group }\\\begin{array} { | c | c | c | c | } \hline \text { Under } 20 & 20 \text { to } 29 & 30 \text { to } 49 & 50 \text { and Over } \\\hline 105 & 110 & 122 & 139 \\113 & 101 & 114 & 115 \\108 & 112 & 128 & 136 \\114 & 127 & 124 & 124 \\123 & 123 & 125 & 123 \\\hline\end{array}\end{array}$$ Degrees of freedom for the between-treatments sum of squares would be:

A) 3.
B) 19.
C) 17.
D) depends on ?.