Why are Flowers considered as the reproductive part of a plant

because it houses the male and female parts of the plant which produce the male and female gametes

Flowers are called reproductive structures of plant as they contain both male and female parts which reproduces to produce pollen grains and eggs. Each of them fertilizers and produces embryo which eventually produces new plant.

the answer is; comparing the frequency of collisions with and without the device

this makes the anti-collision system an independent variable and the collisions a dependent variable. if there are fewer collisions with an anti-collision system that without, then it can be stated that the system is a success. essentially, collisions under an anti-collision system are compared with the frequency of collisions by cars with the human drivers.