Which of the following describes a positive feedback loop? A. When blood sugar concentration is too low, the endocrine system secretes hormones that increase blood sugar concentration to a normal level.
B. When the body senses that the heart rate is very high, it secretes hormones that decrease the heart rate.
C. When blood sugar concentration is too high, the endocrine system secretes hormones that decrease blood sugar concentration to a normal level.
D. When someone is exercising intensely, the body secretes hormones that increase oxygen supply for cellular respiration.

frederick william of brandenburg-prussia trained his son, frederick, to be a hardy soldier. but frederick disliked rifle shooting and horseback riding. unlike his father, he was interested in french literature. he enjoyed poetry and music and, like some others of the enlightenment, he scoffed at religion. his father thought him soft, frivolous and unmindful of his duties. and when frederick refused to put his signature on a right to succession, for a few moments his father strangled him.

the pogroms became known as kristallnacht, the "night of shattered glass," for the shattered glass from the store windows that littered the streets. the morning after the pogroms 30,000 german jewish men were arrested for the "crime" of being jewish and sent to concentration camps, where hundreds of them perished.

this forms a narrow, steep sided inlet (sometimes deeper than 1300 metres) connected to the sea. the terminal moraine pushed down the valley by the glacier is left underwater at the fjord’s entrance, causing the water at the neck of the fjord to be shallower than the main body of the fjord behind it.