<span>The answer is U.S. involvement in Vietnam. Before the assassination of President
Kennedy, Kennedy had plans for withdrawing American troops from Vietnam. When Johnson became president after Kennedy
died, he increase the number of U.S. troops in Vietnam. In addition, he launched a bombing camping in
the North. Despite increase of troops
and a relentless bombing campaign, the North continued to pour into the South
through underground tunnels and using guerilla tactics against American soldiers. After the Tet Offensive, Johnson decided to
slowly withdraw troops from the country.
Later the North conquered the South and Vietnam became one country after
communist rule.</span>
Option 3: children given water to drink
Answer:
Explanation:
A control group in an experiment is a group separated from the rest of the experiment where the independent variable being tested is not exposed. It is the group not receiving the treatment.
Answer:
There are four forces of evolution: mutation, gene flow, genetic drift, and natural selection. Mutation creates new genetic variation in a gene pool. Gene flow and genetic drift alter allele frequencies in a gene pool