John is considering establishing a health savings account. Which of the following statements regarding health savings account (HSA) is correct?

a) Contributions by an S corporation to a 2% shareholder-employee's HSA for services are not included in the employee's W-2 and not deductible by the S corporation.

b) The taxpayer owns the account and the account moves with the taxpayer even if he changes employers.

c) The taxpayer can be enrolled in Medicare or be claimed as a dependent on another's return.

d) Both eligible spouses can have a joint HSA account.

(This question is in regards to 2018 tax year).