Answer: Requirements phase
Step-by-step explanation:Requirement phase in the SDL(secure development life-cycle) is the phase where the security is fused with integrity part for any product. This mechanism is done to know about the requirement of the product in the security field. This is done to achieve the completeness in the product and to recover the mistakes that had happened earlier in the product due to security issues.
Other phase given in the option are for making the code, designing the model of product and testing the products aspects respectively.