Which is the tallest tree?

Statement $S$: $Sequoia$ $sempervirens$ is an example of an angiosperm.
Statement $R$: $Eucalyptus$ is the tallest tree in the world.

In which of the following is the gametophyte not an independent,free-living generation?

During which geological period did the order $Gnetales$ of gymnosperms evolve?

Plants that have open or naked seeds are known as ......

Which major change occurred in the germination of spores during the evolution of seeds?