Which of the following system calls results in the sending of SYN packets?

What is the maximum size of data that the application layer can pass on to the TCP layer below?

If a class B network on the Internet has a subnet mask of 255.255.248.0, what is the maximum number of hosts per subnet?

The use of multiple register windows with overlap causes a reduction in the number of memory accesses for
$$1.\,\,\,\,$$ Function locals and parameters
$$2.\,\,\,\,$$ Register saves and restores
$$3.\,\,\,\,$$ Instruction fetches