"Mechanical" would be the kind of reproductive isolation among the choices given in the question that has been observed in these two species. The correct option among all the options that are given in the question is the first option or option "A". I hope that the answer has come to your help.
The answer would be 25%
Carbon 14 is radioactive material with 5700 year of half-time which will change it into carbon-12, a more stable substance. If the age of the fossil is 11,400 years old, then the amount of half-time passed would be: 11,400 years/ (5,700years/ half-time)= 2 half-time.
Since it undergo 2 half-time, the percentage should be: 100% * (1/2)^2= 25%
The cell wall because of the fact it is present in the plant cell and not in the animal cell
Answer
B: by turning on a battery-powered radio to hear music
