Which of the following is the Maclaurin series of f(r) = cosh(-a)? (-1)" xan (2n)! (a) n=1 (-1)" 2n-1 (2n 1)! (b) n=1 (c) (2n)! n=0 (d) (2n)! n=1 (-1)" 2n (2n)! (e) n=1