Emotional labor refers to the process of managing feelings and expressions to fulfill the emotional requirements of a job. This typically involves controlling one's emotions and displaying certain feelings in order to adhere to workplace expectations or customer service standards. So, the correct definition from your options is:
Controlling feelings in order to behave appropriately on the job.
This concept is often discussed in contexts such as service industries, healthcare, and other roles where emotional display is a part of the job requirements.