The correct answer is 65535.

TCP and UDP use 16 bit port numbers so the numeric range runs from 0 through 65535. Because port 0 is reserved and not available for normal service assignment the usable port numbers for services are 1 through 65535 which yields 65535 distinct assignable ports on a single host.

The option 1024 is incorrect because that number marks the boundary between well known ports and higher ports. Well known ports occupy 0 through 1023 and 1024 is simply the first non privileged port rather than the total count of available ports.

The option 49152 is incorrect because that value is the conventional start of the dynamic or private port range assigned by IANA rather than the total number of ports available on a host.

The option 65536 is incorrect because port numbers are limited to 16 bit values so the maximum numeric port is 65535. The value 65536 is not a valid port number and when you exclude the reserved port 0 the assignable count is 65535.

Full AWS Practitioner Certification Question