According to principles of good grammar and style, which of the following is the best option?
a. Participants were asked to view the screen, think of the picture that most represented their mother, then press the button.
b. Participants were asked to view the screen, then they thought of the picture that most represented their mother, and they pressed the button to indicate their choice.
c. To select the picture that most represented their mothers, participants were asked to view the screen, then press the button that best represented their mother.
d. Participants were asked to look at a screen. Then, participants were asked to think of the picture that most represented their mother. Finally, participants were asked to press the button representing their choice.