Unobstructive research differs from other survey research in that C. it doesn't have an impact on the subject being studied.
Rationale:
Unobstructive research involves the method of collecting data wherein the researcher is physically not present in front of the subject. The reason being that the subjects may alter there behaviour towards the researcher and it may affect the nature of the colected data.
After pollination and fertilization following changes occur in a flower: (i) The petals, stamens, style and stigma of the flower fall off. (ii) Sepals dry up and hold the ovary. (iii) The ovules confined in the ovary develop into seeds.
The ancient Egyptians used the stars to tell when a flood was going to happen. Every summer a flood would happen but this also happened when the bright star Sirius rose before the sun.
Hope that helped ^^