How can a plasmid be described?
a. a small organelle
b. a small loop of dna
c. a prokaryotic ribosome
d. a prokaryotic membrane

Option B,

Explanation:

Plasmids resembles the shape and size of a small circular DNA strand that lies with in the the cytoplasm of a bacterium or protozoan. Thus option B is the correct answer

They are different from normal cell's chromosomal DNA and usually exists naturally in bacterial cells and some Eukaryotas. They  have the ability to replicate independently of the chromosome and thus are mainly used in laboratory for experiments involving gene manipulation

Hence, option B is correct

hydrogen is a compound or a single element and a element is a pure substence that cannot be separated into simpler subtances

clorine is a compound its a chemical substance that forms when two or more different elements combine

so both hydrogen and clorine are compounds

blood enters the heart through two large veins, the inferior and superior vena cava, emptying oxygen-poor blood from the body into the right atrium of the heart. as the ventricle contracts, blood leaves the heart through the pulmonic valve, into the pulmonary artery and to the lungs where it is oxygenated.