Which of the following best describes reproductive structures common to both gymnosperms and angiosperms?
a) seeds form after combining pollen and egg cells during sexual reproduction
b) male pollen grains and female egg cells in the same reproductive organ
c) cones containing seeds that are eaten and carried away by animals
d) flowers designed to attract pollinators to assist in fertillization

Which statements best describe the differences or similarities between a comparative investigation and an experimental investigation? check all that apply. experimental investigations are best for showing cause-and-effect relationships, while comparative investigations do not necessarily show this type of relationship. comparative investigations are often impractical and unrealistic, while experimental investigations are the most practical and realistic kinds of investigations. comparative investigations allow for the use of a wide range of variables but do not have a control group, while experimental investigations involve variables that can be controlled. both experimental investigations and comparative investigations are designed to answer scientific questions. both experimental investigations and comparative investigations focus on making observations rather than collecting new data.