Final answer:
Sex can be determined by the presence of two X chromosomes or an X and a Y chromosome; the temperature at which the eggs are incubated; and the ratio of X chromosomes to the number of sets of autosomes, but not by the number of Barr bodies present.
Step-by-step explanation:
The only mechanism that does not participate in sex determination from the ones provided is (b) the number of Barr bodies present. The presence or absence of Barr bodies is indicative of how many X chromosomes are present in an organism, but it does not directly determine sex.
In most mammals, such as humans, sex is determined by the sex chromosomes: XX leads to a female and XY leads to a male. This is known as the XY system. However, birds use a different chromosomal system (ZW for females and ZZ for males); regardless, the principle remains the same. And some reptiles, like certain species of turtles and alligators, have sex determined by the incubation temperature of their eggs – this is referred to as temperature-dependent sex determination.
Lastly, in some species of insects, the ratio of X chromosomes to autosomes can determine sex. This is known as an X:A ratio and it is referred to as the X0 system. In these cases, females have two X chromosomes (XX or X0) and males have only one X chromosome (X).
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