From cogbooks module 7.1: how could something as complex as the behavior of ant-parasitizing lomechusa (staphylinid beetles) have evolved?

these are beetles with special glands, behavior, and body-shape that trick ants into taking them into their nests. inside the ant-nest, these beetles act as parasites, feeding on ant brood and being fed by the ants.

a. these complex behaviors may have arisen gradually through natural selection.
b. complex structures and behaviors such as lomechusa beetles often appear suddenly in the natural world - with little natural precedent.
c. many lomechusa beetles already have pre-existing glands and behaviors that could potentially be co-opted and modified through time.
d. both a and c from

A. These complex behaviors may have arisen gradually through natural selection.

Explanation:

Lomechusa beetles have pre-existing glands and behaviors that can be easily co-opted and changed through time

americans began to notice growing differences between the northern and southern sections of the country. there were more people living in cities in the north, which made it more urban. more people lived on farms in the south, which made it more rural. while many people were farmers in the northern states, there were now other ways to make a living, such as working in mechanical cotton gins factories manufacturing cloth, tools and other goods. people in the north supported high tariffs on goods imported from europe because the extra cost encouraged people to “buy american” instead. in the southern states, planters did not like tariffs because they sold most of their production to europe and bought their tools from there as well. southerners believed the protective tariff was something that only northern factory owners keep their profits high. so the southern politicians came up with an idea. they would opt out. they would simply ignore the protective tariff. it was ‘null and void’ in south carolina. the state would not collect the taxes on goods imported into south carolina, no matter what the president said they had to do. this decision led to the nullification crisis.

9.9 years

a = p(1 + rt) . . account balance after time t at rate r starting with principal p

3000 = 2500(1 + 0.0202t) . . filling in the given numbers

1.2 = 1 + 0.0202t . . divide by 2500

0.2 = 0.0202t . . . subtract 1

0.2/0.0202 = t ≈ 9.901

it will take about 9.9 years for the account balance to reach $3000.