Tetanus, often called lockjaw, is a serious disease that can arise from an infection caused by a puncture wound. a tetanus vaccine became popular in the 1940s when it was used to protect soldiers during world war ii. the chart shows tetanus cases in the united states since 1947.

answer; polycythemia is the correct answer;

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation:

a physical change is being made.