Final answer:
The nurse advises the parent to allow the child to engage in imaginary play. Imaginary play is a normal part of a preschool-age child's development and helps enhance their creativity and social skills.
Step-by-step explanation:
The nurse advises the parent to allow the child to engage in imaginary play (option c).
Imaginary play is a normal part of a preschool-age child's development. It allows them to use their imagination, enhance their creativity, and learn social and problem-solving skills. Interacting with an imaginary friend is also common and can help the child explore their emotions and develop empathy.
Encouraging the child to play with other children (option a) and telling the child that the playmate is not real (option b) may limit their imaginative play and hinder their development.