In which plant are the largest sperms found?

The male prothallus $(gametophyte)$ in $Pinus$ consists of:

What is correct for conifers?
$I$ - Leaf is like a needle,$II$ - Thick cuticle,$III$ - Thin cuticle,$IV$ - Sunken stomata,$V$ - Stomata absent

The endosperm of gymnosperms is $...$.

The tallest living tree in the world is ........

What is the nature of the ovule in gymnosperms?