How are the senate leaders chosen?

they are appointed by the president of the senate.
they are elected within each party.
they are elected by the whole senate.
they are appointed by the president pro tempore.

Option B, They are elected within each party, is the right answer.

Explanation:

The leaders of the Senate of the United States are elected by the members of their own party before the commencement of each congress. Depending on the party in power, one follows as majority leader and others as minority leader.

These elected leaders become the spokesperson of their respective parties. However, the daily legislative affairs and programs are scheduled by the majority leader.

b

Explanation:

on edge

the invasive species was introduced due to commercial purpouses, as there was a demand for fur clothes and hence, a business opportunity connected to this product. actually, it was when the nutrias scaped, causing harm to the us ecosystems when they acquired the status of invasive species. in this case they have caused an environmental problem, but it could have affected also economic interests or even human health.