What was a major benefit of bipedality? better detection of predators freed the hands for other uses faster locomotion could jump over streams and barriers?

The right answer is freed the hands for other uses.

bipedality is also more economic than tetrapedality, but it is not as fast and does not offer a high jumping skills.

The standing position has an advantage in reproduction because it has become attractive to females and more or less successful imitation in males, depending on their abilities, but bipedalism is a disadvantage in childbirth.

the sea slugs belong to the same class

of those who start drinking before they're 15 will develop alcohol dependence