As a general rule of thumb, an infant should her birthweight by her first birthday.

The rule of a thumb is a type of guideline or principle which is being followed by some of the people. In the statement above, the correct answer in the space provided is triple. It is because it is expect that the baby should have a weight triple than of her birth weight because it is expected and it is already a practice that is being done and experienced by parents who have gave birth to their child.

Ithink or blue