Its because a long spine cacti can reproduce more because it has more survival capacity than the short spine cacti and because of this reason the short spine cacti cannot protect it self because it has a shorter spine that could protect itself from danger.
Student 4 is correct. The farther the planet is from the Sun, the less pull it exerts on it.
Cancer is a mutation that occurs during the cell cycle, usually when it develops and grows it means the mutation was able to go through the cycle undetected at checkpoints so the cell was not destroyed by the lysosomes.
