Charles Darwin's scientific contribution can best be described as a. development of the concept of evolution via natural selection.
b. development of the concept of evolution via genetic mutation.
`c. development of the idea that animals evolved from plants.
d. development of the idea that fungi and plants are different.

An astronaut in space cannot use a scale or balance to weigh objects because there is no gravity. but she does have devices to measure distance and time accurately. she knows her own mass is 77.4 kg , but she is unsure of the mass of a large gas canister in the airless rocket. when this canister is approaching her at 3.50 m/s , she pushes against it, which slows it down to 1.30 m/s (but does not reverse it) and gives her a speed of 2.60 m/s . what is the mass of the canister?