Answer:
The correct answer is sponsored inmail.
Step-by-step explanation:
InMail messages work like LinkedIn private mail. This advertising option allows you to send messages to segmented users through the LinkedIn email client (LinkedIn Messenger).
A very interesting feature of sponsored InMail messages is that users only receive them if they are active on LinkedIn, which increases the chances of success. To make them work, try to personalize the message to the fullest, be concise and make the call to action very clear.