Correct Answer:
See explanation below.
Explanation:

Firewalls # VPN tunnel down
The IPsec tunnel between on-prem Firewall 1 and cloud Firewall 2 (ipip0/ipip2) is down, so no traffic can traverse to the cloud.
Application NSG # Misconfigured rule
There's a "block" rule for 10.3.9.0/24 # 192.2.1.0/24, preventing legitimate on-prem clients from reaching Application A.