12. because mandisa always picked up her newborn daughter when she cried, her daughter is now a real crybaby. in this case, picking up the infant served as a(n) for crying.

positive reinforcer

Explanation:

Positive reinforcer:-

Positive reinforcer in the operant conditioning, involves addition of the reinforcing stimulus which is followed by a behavior and it makes the behavior further more likely to happen in future. This behavior is strengthened when the favorable event or the outcomes success or occurs after the action stimulus.

Hence, in the given question, as Mandisa's daughter is serving positive reinforcer as she has a reinforcing stimulus of crying that her mother will pick her in future also.

first, the romans stayed isolated because they had to defend their own territories from neighboring cities that were harassing them, like the etruscans. second, once the romans managed to defeat their neighbors, and started to expand their territory, they started to build roads and bridges. finally, now that the romans have covered their territory with roads functioning as highways, they could mobilize their legions faster to assemble larger military units in a specific place.

answer; ///approx///5,000 miles;