The correct answer is Regional managed groups.

Why?

• Regional managed groups distribute instances across multiple zones within a single region, which is ideal for achieving high availability by spreading instances across three zones.
• They also offer automatic scaling, healing, and rolling updates, thereby improving application resilience.

Why not the others?

• Zonal managed groups deploy instances within a single zone, lacking the desired redundancy across multiple zones.
• Multi-Regional managed groups is not a valid Google Cloud instance group type. Regions encompass zones, making this option incorrect.
• Multi-Zonal managed groups, while seemingly correct, is not the official terminology used in Google Cloud; the correct term is Regional managed groups.