As a result of sensitivity analysis, you ended up with the slope of the sensitivity graph with respect to first

 

 cost equal to $-50.$ It means that Question $29$ options: 

 

 An increase in first cost by $1\%$ decreases the present worth of the first costs by $$50$ 

 

 An increase in first cost by $1\%$ decreases the present worth of a project by $$50$ 

 

 An increase in first cost by $1\%$ decreases the present worth of a project by $50\%$ 

 

 An increase in first cost by $$1$ decreases the present worth of a project by $$50$ 

 

 An increase in first cost by $$1$ decreases the present worth of a project by $50\%.$