In which of the following examples would we see the influence of a default option? (You can choose more than one.)
a. A doctor recommends continuing treatment, but the ultimate decision of whether to continue treatment is left up to the patient.
b. A website automatically checks the option “share my activity with my friends on Facebook” when users sign up.
c. Pets from an animal shelter are automatically spayed or neutered unless the owner would prefer them not to be.
d. A mobile phone user has to enter a choice at start-up between installing a special feature or not. The user is informed that most people choose to install the special feature.