Largest open interval of convergence for the power series about c=0 representing the function f(x)=2/(x^2 +4)?

...don't worry about endpoints





possible solutions...





a. (-1/6, 1/6)





b. (-1/4, 1/4)





c. (-1/3, 1/3)





d. (-1/2, 1/2)





e. (-1, 1)





f. (-3/2, 3/2)





g. (-2, 2)





h. (-3, 3)





i. (-4, 4)





j. none of these

Largest open interval of convergence for the power series about c=0 representing the function f(x)=2/(x^2 +4)?
d