I think the correct answer is C
Answer:
Increase
Explanation:
Resonance is a phenomenon which occurs when a body A in motion set another body B into motion of it own natural frequency. So for resonance to be minimize in a body is to increase the width to span ratio. So as to reduce the overall vibration which affects directly building resonance, the stiffness or trusses and girders should be increase. The increase in this aspect helps to reinforce building structure and support.
Answer: to only change one factor in an experiment or test
Answer:
Part a)

Part b)

Explanation:
Part a)
For force conditions of two blocks we will have


now from above equations we have


now we know that


now from above equation we have


Part b)
When heavier block is removed and F = 908 N is applied at the end of the string then we have



ummmm it might be 300... i used a calculator
sorry if it is wrong