Exam 1Y0-231 topic 1 question 34 discussion

Scenario: A Citrix Administrator currently manages a Citrix ADC environment for a growing retail company that may soon double its business volume. A Citrix ADC MPX 5901 is currently handling web and SSL transactions, but is close to full capacity. Due to the forecasted growth, the administrator needs to find a cost-effective solution.
Which cost-effective recommendation can the administrator provide to management to handle the growth?