A hiker finds a smooth, rounded pebble along the shore of a stream that is flowing down from a mountain. Which of these most likely caused the pebble to have this appearance?

A, b,c or d !?
PLS I NEED HELP

Which sentence best expresses the differing opinions of these two book reviews?

Dna has unique properties that allow it to accurately retain genetic information, even after multiple rounds of replication. one aspect of dna that allows it to accurately store genetic information is the base pairing from chargaff\'s first rule of the four nucleotide bases. if the c content of a dna molecule is 22%, what are the percentages of the remaining bases?

Out of the seven main animal groups (fish, mammals, birds, insects, reptiles, amphibians, and arachnids), how many contain members with internal backbones? a. 5 b. 3 c. 7 d. 1