Considering that males are produced by Klinefelter (XXY) syndrome, XYY and normal XY chromosome combinations, and females are produced by Turner (XO) syndrome, triple-X (XXX) and normal XX combinations, it is obvious that

a. maleness is caused by the minimal presence of one Y chromosome.
b. maleness occurs in the absence of two or more X chromosomes.
c. maleness is caused by the presence of only one X chromosome.
d. femaleness is caused by the presence of two or more X chromosomes.

answer; i believe its echoic memory,it is believed to last three to four seconds; good luck

the supermassive black hole is in the middle of the galaxy.

a researcher conducts an experiment on the secretion of a particular hormone in mice. scientists inject mice with a substance that stimulates the production of the hormone. the scientists then test the levels of hormones produced by the mice. the tool used to measure the hormones consistently detects the levels at 10 points lower than the actual hormone levels in the mice. this tool makes measurements, but the measurements aren't .

explanation:

no u

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.