<u>Answer:</u>
C. a horizontal shift of 9 units left
<u>Step-by-step explanation:</u>
Look at this helpful chart:
Vertical Translations
translation up k units: g(x) = f(x) + k, where k > 0
translation down k units: g(x) = f(x) – k, where k > 0
Horizontal Translations
<u>translation left k units: g(x) = f(x + k), where k > 0</u>
translation right k units: g(x) = f(x – k), where k > 0
The change happening in Martina's graph is therefore a horizontal translation to the left.