The answer is A, friction.
Friction is the force that resists movement, and that's why oil is used as a lubricant and why ball bearings are used for machines that need to move with very little friction(i.e. bike wheels, roller skates, fidget spinners)
Answer B is too vague
C will probably reduce efficiency greatly, but not specifically in a way that turns work into thermal energy.
D is the same as C, except that it places the blame on the person using the machine, not the machine itself.
Hope I helped clear it up for you :)
<span>The heart contains four chambers: upper left atria, upper right atria, lower left ventricle and the lower right ventricle. Oftentimes, the right atria and right ventricle are together referred to as the "right heart" and the left atria and left ventricle are referred to as the "left heart", however there are still four separate chambers.</span>
Answer: Caecum of the intestines
Explanation:
The caecum is located in between the large intestine and the ileum and the colon. It is referred to as blind gut because one end of it is close and the other continues into the colon.
I’m guessing in the chromosomes
Answer:
an ecosystem consists of a population of organism and it's physical environment,and a population is made up many different communities of organism.
