SA CIVIL AVIATION REGULATIONS
PART 91: GENERAL AVIATION AND OPERATING FLIGHT RULES
91.06.16 MANDATORY RADIO COMMUNICATIONS IN CONTROLLED AIRSPACE

1. Radio communication failure (RCF) procedures – General

(1) When an aircraft fails to establish contact with the aeronautical station on the designated frequency, it shall attempt to establish contact on another frequency appropriate to the route. If this attempt fails, the aircraft shall attempt to establish communication with other aircraft or other aeronautical stations on frequencies appropriate to the route. In addition, an aircraft shall monitor the appropriate VHF frequency for calls from nearby aircraft or aeronautical stations.

(2) If these attempts fail, the aircraft station shall continue to transmit position reports and its intentions as appropriate on the designated frequency or frequencies, preceded by the phrase “Transmitting Blind”. Such messages shall be transmitted twice and, if necessary, include the addressee(s) for which the message is intended

(3) If no communication is received or other indication that one-way communications are possible, the aircraft shall set its transponder to Code 7600 and proceed with the lost communications procedures.

2. RCF procedures – VFR

(1) If the communications failure occurs while operating in accordance with VFR, the aircraft shall continue to fly in visual meteorological conditions (VMC) and land at the nearest suitable aerodrome using –

(a) the standard RCF arrival procedures prescribed in Appendix 1 to this TS; or
(b) if other procedures have been published by the Director for a specific aerodrome, in accordance with such procedures.

(2) The operator shall report its arrival by the most expeditious means to the appropriate air traffic services unit (ATSU).

Let's analyze the given options:

Leave controlled airspace, broadcast blind, squawk 7600, and land at a suitable airfield. → INCORRECT. Leave controlled airspace is not one of the steps specified in PART 91.

Broadcast blind, squawk 7600, return to the field from where you took off, enter the circuit and land. → INCORRECT. According to PART 91 the aircraft should land at the nearest suitable aerodrome which may be different than the departure aerodrome.

Broadcast blind, squawk 7600, route to the nearest airfield, enter the circuit and land. → CORRECT. The pilot should keep transmitting blind, set 7600 on the transponder and land at the nearest suitable aerodrome.