Final answer:
The independent variable for Sasha's experiment is the b) shape of the solar cooker.
Step-by-step explanation:
The independent variable for Sasha's experiment would be the shape of the solar cooker. The independent variable is the variable that is deliberately changed or manipulated by the experimenter in order to observe its effect on the dependent variable. In Sasha's experiment, she wants to test the hypothesis that the air temperature will be greater in the round solar cooker compared to other shapes. Therefore, she will change the shape of the solar cooker to see if it has an impact on the air temperature. The other options listed are not the independent variable in this experiment. The colour of the solar cooker, air temperature, and degrees Celsius are either irrelevant or dependent variables that are being measured, not manipulated.