The given statement is true.
The majority of the chronic diseases are not accredited to a single cause, some of the poor lifestyle choices like overuse of alcohol, smoking, lack of physical activity, poor diet, and insufficient relief of chronic stress are the major contributors in the advancement and development of preventable chronic ailments, like type 2 diabetes, obesity, cardiovascular disease, hypertension, and many kinds of cancer.
A memory B cell is kinda of how it sounds it has a memory of what your body has fought before such as a virus and can stimulate a response quicker then the first time you encountered it.
If you lack memory B cells your body doesn't built up the same immune response when you come into contact with the virus again.
"Vaccination would prevent further disease" Incorrect, a vaccine lets you build up memory cells to combat the disease if you lack them you cannot build up a defense.
"Vaccination would not prevent further disease" Correct, a vaccine can be a dead version of a virus or parts of a virus that shows your body what to respond to quickly in the future. If you body cannot make memory b cells it wouldn't help to use a vaccine. Your body wouldn't keep a memory of it being bad.
"You would not produce antibodies" Even if your body does not remember a particular virus it does produce antibodies to combat it just not as quick or efficiantly as something it has come into contact with before and produced memory cells.
"You would over produce histamine" Incorrect, different process for that histamine.
Answer: genotypic ratio 2/4
Phenotypic ratio 4/4 is the same
Explanation: suppose RR is the dominant female and Rr is the heterozygous male. Then after the cross genetically 2 have RR and 2 have Rr ratio. But phenotypically all 4 are the same.
The answer is
B........................................
Isotonic solution.
Since it has the same salt concentration as the cell the solution is neither hypotonic or hypertonic.