Answer:
A) Temperature
Step-by-step explanation:
Independent variable in an experiment is the variable that the experimenter changes or manipulates in order to bring about a measurable response.
In this question given, the data is portraying the Temperature versus Photosynthetic rate. This means that the experimenter is testing to see the effect of varying temperatures on the photosynthetic rate. Hence, the TEMPERATURE is the independent variable because it is the variable being changed.