What would occur if a fetus's villi tissue ruptured?   the maternal tissue of the placenta would be damaged, causing bleeding. the maternal and fetal blood would mix, causing an immune reaction. the umbilical vein would be blocked, preventing waste export from the fetus. the umbilical artery would be blocked, preventing oxygen import to the fetus.

answer; //the above statement is (false);

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.