The answer is A. Decreasing the distance between the particles by a factor of 3.
The Universal Law of Gravitation is :
F = Gm₁m₂ / r² (where 'r' is the distance between them)
Since force is inversely proportional to the square of the distance between them, distance has to be decreased by a factor of 3 to increase the force to 9 times the original force.
Answer:
Antibody molecules that are secreted by plasma cells mediate the humoral immune response. The antigen that binds to the receptor of the B-cell antigen signals B cells and is internalized and transformed into peptides that activate the armed helper at the same time.
Explanation:
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