When are infants first able to use the arms in complementary roles, such as holding a box lid open with one hand while the other removes an object from the box?

The last half of the second year

Explanation:

When are infants first able to use the arms in complementary roles, such as holding a box lid open with one hand while the other removes an object from the box?

During the infant and toddler years, children develop basic manipulation skills, their motor skills develop as their whole body starts to move and become more stable, they also learn to do more things with their hands. In infant lifting one's head, rolling over, crawling and siting up are example of development of basic skills. The development of these roles are graded occurring to their age of development. For example an infants is first been visually guided at 4-7 month of age and also able to select a uni-manual reach at the last half of the first year

answer is b.shrapnel

answer; /// i believe the correct answer is (when one group has an extremely high score at pretest;