Call options are permitted by the IRS, but most custodians don't allow them because the odds are that you'll be holding a contract that you can't legally exercise because of the contribution limits. With a contribution limit of just $5K, it's pretty easy to buy a call that would require more cash than you can contribute to exercise. I know what you're thinking - you intend to sell the call, not exercise it, when the time comes - but most compliance departments don't see it that way. They see you buying a contract that they're not going to let you exercise.
That doesn't really make sense...maybe it is time to find a new broker?
You might not be able to contribute enough new cash to exercise a call option, but technically the entire balance of your account can be liquidated to buy the shares.