Which payments are compulsory for a GSM business entrepreneur.

The question asks which payments are compulsory for a GSM business entrepreneur.

• I. Insurance fee: While highly recommended for risk management, insurance is generally not a legally compulsory payment for all businesses to operate.
• II. Income tax: All businesses are legally required to pay income tax on their profits. This is a compulsory payment.
• III. Business registration: It is compulsory to register a business with the relevant authorities to operate legally. This is a compulsory payment/fee.
• IV. Advertisement fee: Advertising is a business expense for marketing, but it is not a compulsory payment required by law to establish or operate the business. Therefore, only income tax and business registration are compulsory.

The compulsory payments are II (Income tax) and III (Business registration).
The correct option is C.

$$\boxed{\text{C}}$$

The question describes a partner in a two-man partnership GSM business deciding to walk away and asks for a likely consequence.

• When a partner leaves a partnership, especially in a two-person setup, their capital contribution to the business is typically withdrawn or needs to be bought out by the remaining partner. This directly leads to a reduced business capital.
• Reduced liability (A) might occur for the remaining partner in some structures, but the immediate impact on the business's resources is capital reduction.
• Increased profit margin (C) is unlikely, as the business might face operational challenges or reduced capacity.
• Reduced customer satisfaction (D) is a potential indirect consequence, but not the primary direct impact on the business's financial structure.

The most direct consequence of a partner leaving a two-man partnership is a reduction in the business's capital.
The correct option is B.

$$\boxed{\text{B}}$$