Which contraceptive method is 100 percent effective at preventing pregnancy?
condom
oral hormonal methods
sterilization
abstinence

The correct answer is D. Abstinence

Explanation:

A contraceptive method or birth control method refers to a method used to avoid pregnancy or reduce the probability of getting pregnant. From antiquity, there have been different contraceptive methods but only in the last decades, methods have been designed based on science and its effectiveness has been studied.

Because of this, nowadays there are many contraceptive methods such as pills, condom, and implants that are about 80% to 95% effective, sterilization that is a around 98% effective and natural methods that have a lower percentage of effectiveness. But the only method that has been proven as completely effective or 100% effective is abstinence because by avoiding any type of sexual intercourse it is virtually impossible an egg can be fertilized by a spermatozoid.

4.) metal

"-the movement of carbon from the nonliving environment into living things and back to the environment

-carbon is the essential component of proteins, fats, and carbohydrates (which make up all organisms)

-carbon exists in air, water, and living organisms

-producers convert carbon dioxide in the atmosphere into carbohydrates during photosynthesis

-bacteria in the atmosphere cycles through the system in filtration units

-in cellular respiration, carbon is released back into the atmosphere as carbon dioxide

-some carbon is stored in limestone (forming one of the largest "carbon sinks" on earth)

-largest carbon reservoir on earth= limestone

-carbon stored in the bodies of organisms as fat, oils, or other molecules may be released into the soil or air when the organism dies

-this may form deposits of coal, oil, or natural gas (fossil fuels, which increased the atmospheric carbon dioxide)

-fossil fuels store carbon left over from bodies of organisms that died millions of years ago

-they are located in the surface of earth, deep within the earth and beneath the ocean floor."    

explanation:

the universal gravitation equation. since the gravitational force is directly proportional to the mass of both interacting objects, more massive objects will attract each other with a greater gravitational force. if the mass of one of the objects is doubled, then the force of gravity between them is doubled.