Employers often set up the option for employees to contribute to Flexible Spending Accounts $($FSAs$).$ This option offers many advantages to employees, but there are several disadvantages for employees as well. Which of the following is one of those potential pitfalls for employees?

a$)$ FSAs must be used with high$-$deductible health insurance.

b$)$ Employees with FSAs are not permitted to contribute pre$-$tax income into the FSA, so there is no tax$-$savings for the employee.

c$)$ The FSA participant's annual contribution to the FSA must be spent by the specified deadline or the person loses that money $($i$.$e$.,$ "use it or lose it$").$

d$)$ The FSA participant is not able to earn investment income on the money he or she has contributed to the FSA.

e$)$ Both c$.$ and d$.$