After setting up separate child advertisers for your client in Campaign Manager 360, the next step to prepare the client’s account is to create a campaign for their new line of gloves.

• Choose optimal placements for their glove launch.
• Upload your glove specific creatives into your account.
• Select the ad sizes for your glove creatives.
• Create a campaign for their new line of gloves.

The correct answer is: Create a campaign for their new line of gloves.

Explanation: Following the creation of child advertisers in Campaign Manager 360, the next crucial step is to prepare the client’s account for campaign execution. Child advertisers offer account segmentation, but a campaign is essential for launching and managing specific promotional efforts. Thus, creating a campaign for their new line of gloves is the appropriate next step. This campaign will organize placements, ads, and creatives, enabling precise tracking and optimization. This action moves beyond account organization to active campaign management, ensuring the new glove line receives targeted promotion within CM360.