Which of the following is commonly known as the 'Chilgoza Pine'?

If the pollen grain of $Pinus$ contains $6$ chromosomes,then how many chromosomes will its endosperm have?

Cataphylls are

The $Cycas$ plant is similar in appearance to which of the following?

Plants in which seeds develop on sporophylls and are not enclosed by fruits are classified as -

Select one of the following pairs of important features distinguishing $Gnetum$ from $Cycas$ and $Pinus$ and showing affinities with angiosperms.