$6\mathrm{.}15$ Find the overhead fraction for a full K$-$ary tree implementation with space requirements as follows:

$($a$)$ All nodes store data, K child pointers, and a parent pointer. The data field requires four bytes and each pointer requires four bytes.

$($b$)$ All nodes store data and K child pointers. The data field requires six$-$ teen bytes and each pointer requires four bytes.

$($c$)$ All nodes store data and a parent pointer, and internal nodes store K child pointers. The data field requires eight bytes and each pointer re$-$ quires four bytes.

$($d$)$ Only leaf nodes store data; only internal nodes store K child pointers. The data field requires four bytes and each pointer requires two bytes.