Explanation
The SRX Series device will drop packets from the infected hosts with a threat level of 8 and no log message will be generated. This is because the security intelligence profile "ATP_Infected-Hosts" has a rule "Rule-1" that matches packets with a threat level of 8 and the action is to block and drop them. There is no log option specified in the action, so no log message will be generated. Options A and B are not correct because the rule only matches packets with a threat level of 8, not 8 or above. Option C is not correct because the action is to drop, not permit, the packets. References: The answer can be verified from Juniper's official documentation on security intelligence available on their website. Here are some relevant links:
Security Intelligence Feature Guide for Security Devices
security-intelligence | Junos OS
Configure the Security Intelligence Policy on the SRX Series Device