Which of the following statement is correct?

• Phosphate repression can not be eliminated by optimization of nutrient medium, deregulated medium must be used as production strains
• Phosphate repression can be eliminated by optimization of nutrient medium, deregulated medium must be used as production strains
• Phosphate repression can be eliminated by optimization of nutrient medium, regulated medium must be used as production strains
• Phosphate repression can not be eliminated by optimization of nutrient medium, regulated medium must be used as production strains