A stem-and-leaf plot has the following rows: stem 2 with leaves 1, 5, 8; stem 3 with leaves 0, 2, 2, 9; stem 4 with leaves 1, 5. How many…

Each leaf on the plot represents one data value, so count the leaves in every row. The stem $2$ row has leaves $1, 5, 8$, which is $3$ values. The stem $3$ row has leaves $0, 2, 2, 9$, which is $4$ values, and the repeated $2$ counts twice. The stem $4$ row has leaves $1, 5$, which is $2$ values. The total is $3+4+2=9$, choice C. Choice A ($3$) counts only one row. Choice B ($7$) leaves out one repeated leaf or one row. Choice D ($10$) counts the stems as data values too.