1- Paleozoic era
2- mesozoic era
3- Cenozoic era
B. Scientific law
Explanation-
It’s a statement that explains an idea based upon experimental observations. It’s true based on the fact that they have always been observed to be true. It can be in a form of words and be expressed as a mathematical formula.
Examples would be the law of gravity and Boyle’s law of gases.
Answer:
DNA is found in nearly all living cells. ... Although each organism's DNA is unique, all DNA is composed of the same nitrogen-based molecules. So how does DNA differ from organism to organism? It is simply the order in which these smaller molecules are arranged that differs among individuals.
The correct answer is (d) The number of plants and birds increases and the number of snail decreases.
Green plants are eaten by snails, snails by birds, and birds by household cat. If cat is removed from the cycle then the number of birds will increase which will decrease the number of snail in the environment. As there are large number of birds there will be a great demand of snails as a food for birds. Then there will be a decrease in the number of snails because of over eating of snails. There will be an increase in the number of garden plants because very less number of snails are left that will eat garden plants.