Microsoft Defender for Office 365 provides configurable inbound anti-spam policies that enable administrators to filter unwanted email according to sender characteristics, geographic origin, languages, and recipient groups.

Option C is correct because a custom anti-spam inbound policy supports geographic filtering through the From these countries setting and can be scoped to selected recipient groups.

Administrators can configure the policy through the following steps:

Navigate to Microsoft Defender portal → Email & collaboration → Policies & rules → Threat policies → Anti-spam.

Select Create policy → Inbound.

Under Users, groups, and domains, specify Group1 as the recipient group.

Under Bulk email threshold & spam properties, enable From these countries and select the countries or regions from which unwanted messages originate.

Configure the appropriate spam action, such as moving detected messages to Junk Email or quarantine.

This configuration ensures that geographic spam filtering applies specifically to Group1 without altering protection settings for other recipients.

Option A is incorrect because connection filter policies operate on source IP addresses and do not provide the required group-specific geographic filtering.

Options B and D are incorrect because preset security policies do not provide the required customizable country-based filtering settings.

Option E is incorrect because anti-phishing policies focus on spoofing, impersonation, and phishing detection rather than geographic spam filtering.

Implementation consideration: Recipient-group targeting supports mail-enabled security groups, distribution groups, and Microsoft 365 groups. Also, Standard or Strict preset security policies take precedence over custom inbound anti-spam policies for recipients included in those presets.