The correct answer is ufw allow 443/tcp because it allows incoming TCP traffic on port 443, which is the standard port for HTTPS traffic. The answer ufw allow 80/tcp is incorrect as it would allow traffic on port 80, which is the standard for HTTP, not HTTPS. The answer ufw deny 443/tcp is incorrect because it explicitly blocks traffic on port 443 rather than allowing it. Lastly, ufw allow 443/udp is incorrect as it allows UDP traffic on port 443, which is not typically used for web traffic as HTTPS uses the TCP protocol.