Which skill generally indicates a child can stoop and recover by 18 months?

The ability to stoop and recover is a significant milestone in motor skill development for young children, typically seen around 18 months of age. This skill indicates a child's progress in overall coordination, balance, and strength. Jumping on two feet, which involves bending the knees, propelling the body upward, and landing safely, demonstrates not only the ability to create and maintain balance but also indicates that the child has developed the necessary muscle strength and control to navigate such movements.

When a child can jump on two feet, it suggests they have a solid understanding of their body's positioning and can transition into different physical activities smoothly. This proficiency is closely related to the ability to stoop down to pick something up and then return to an upright position without falling, highlighting the overall progress in gross motor development.

The other choices pertain to earlier developmental milestones that typically occur before 18 months. For instance, keeping the head up while prone, sitting up, and pulling to stand are important stages in physical growth but do not directly indicate the complex coordination and balance required for stooping and recovering. Jumping signifies a child's readiness for more advanced physical activities and reflects a greater level of physical competency characteristic of the expected development around 18 months.