Evaluate the indefinite integral ${\displaystyle \underset{\phantom{}}{\overset{\phantom{}}{}}}(\sqrt[\phantom{2}]{t}+1)(\sqrt[\phantom{2}]{t}-1)dt$

Select one:

a$.\frac{t^2}{2}-t+C$

b$.t^2-t+C$

c$.\frac{(\sqrt[\phantom{2}]{t}+1{)}^2}{2}\frac{(\sqrt[\phantom{2}]{t}-1{)}^2}{2}$

d$.$ None of the above