Answer:
Control
Explanation:
Professor Eatwell is trying to study the effects of zinc supplements on young adults' susceptibility to the cold virus. In order to study the effect of zinc supplements it must be made sure that the effects observed during the study is the effect of the zinc supplement solely.
In order for this to happen a control group is used where the group is not given zinc supplements even though the group members think that they are receiving zinc supplements.
The repeated behaviour has been <u>reinforced. </u>
This is deduced from the learning mechanism known as operant conditioning, that consists on reinforcing certain behaviours through rewards or punishments respectively depending on whether the aim is to increase or decrease their frequency.
If there is a positive or rewarding stimulus after the correct behaviour it increases the likelihood of the behaviour repeating again.
The answer would be : The social security Act.
The most important development in providing secure retirement for americans was the Social security Act. The social Security Act provide General Welfare by creating various systems for old-age benefits