The local newspaper receives several complaints per day about typographic errors. Over a seven$-$day period, the publisher has received calls from readers reporting the following number of errors: $4,3,2,6,7,3,$ and $9.$ Based on these data alone, what type of control chart$($s$)$ should the publisher use?

a$.$

p$-$chart

b$.$

c$-$chart

c$.$

Mean chart

d$.$

R$-$chart

e$.$

Mean chart and range chart