Let S(x)=∑n=0∞x2n(2n)!S(x) = \sum_{n=0}^{\infty} \frac{x^{2n}}{(2n)!}S(x)=∑n=0∞(2n)!x2n. This series is the power series representation of which function?
cosh(x)\cosh(x)cosh(x)
cos(x)\cos(x)cos(x)
sinh(x)\sinh(x)sinh(x)
exe^xex