In Junos security policies, rules are evaluated sequentially from top to bottom, and once a match occurs, the subsequent policies are not checked. In the configuration shown, policy1 allows junos-http traffic, and policy3 also matches the same application (junos-http) but denies it.
Because policy1 appears first and already permits this traffic, policy3 will never be evaluated for that same traffic type. Therefore, policy3 is shadowed by policy1.

The proxy ID is used as a final check to verify the peer before IPsec tunnel establishment. The proxy ID is a combination of local and remote subnet and protocol, and it is used to match the traffic that is to be encrypted. If the proxy IDs match between the two IPsec peers, the IPsec tunnel is established, and the traffic is encrypted.

Routing instances: Security zones are local to their routing instance. They cannot be shared between routing instances (Option B is correct). Each routing instance must define its own zones.
Intrazone and interzone traffic: Both types of traffic require policies in Junos OS. Intrazone traffic must have an explicit intra-zone policy to be controlled (Option C is correct).
Sharing zones: Option A is incorrect, as zones cannot span routing instances.
Multiple zones: SRX devices fully support multiple security zones (trust, untrust, DMZ, etc.). Option D is incorrect.
Correct Statements: B and C

The AppID license must be installed and active to enable application identification, which is required for unified security policies to recognize and control nested HTTP applications.
Dynamic application objects must be included in the unified security policies to match and control specific applications identified through AppID, such as Facebook within HTTPS traffic.

Intra-zone traffic: On SRX devices, traffic between interfaces in the same security zone is allowed without requiring a security policy (Option C is correct). Policies are only evaluated for inter-zone traffic.
Junos-host functional zone: This zone is a predefined functional zone that allows administrators to apply policies controlling access to the SRX firewall itself, such as SSH, HTTP, or SNMP traffic (Option D is correct).
Null zone: This zone is a predefined discard zone. Interfaces placed in the null zone drop all traffic. It does not allow policy logging of dropped control plane traffic (Option A is incorrect).
Management functional zone: This is used to define management interfaces, not the "functional zone" as stated in Option B (incorrect wording).
Correct Statements: C and D