Releases energy that is used to pump hydrogen ions from the stroma into the thylakoid compartment.
the figure shows the membrane of the thylakoid. letters from a to e indicate definite structures. letter a indicates the first protein complex of the light-dependent reactions, which is located in the thylakoid membrane. letter b indicates the multiprotein complex between two photosystems. letter c marks the second integral membrane protein complex of the light-dependent reactions. letter d marks the substance inside thylakoid. letter e indicates the flask-shaped structure, which has a canal for hydrogen ions.
a. d
b. a
c. b
d. c
e. e

A. D or electron transport chain

Explanation: first protein complex of the light-dependent reactions, which is located in the thylakoid membrane, and the electron transport chain is also a factor in it but it doesn't mention that.

his research revealed two genetically different groups of prokaryotes, which justified splitting kingdom monera into two kingdoms. the genetic and cellular differences were so great, that these two kingdoms were eventually placed into different domains in the current three-domain system.

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.