Choose letter \(\mathrm{C}\) (for committed fixed cost) or \(\mathrm{D}\) (for discretionary fixed cost) to indicate the type of each of the following described costs.

a. Professional meeting attendance fees

b. Depreciation on office equipment

c. Property insurance premiums

d. Equipment maintenance

e. Sales salaries g. Catered business meetings h. Health insurance premiums i. Research and development costs j. Social media advertising costs k. Internet provider fees