Which group(s) of organisms do not have vertebrae?

According to this cladogram, sharks are MOST closely related to which organism? 

On the diagram, which feature do all organisms inherit?

A common ancestor for both C and E could be at position __.

According to this phylogenetic tree, which creature is the least related out of all pictured?

According to this image, when did the ancestors of Indohyus and Pakicetus diverge?

If a plant has vascular tissue but no seeds, which of the four plant groups here would it fall into?

According to this tree, which of these animal phyla are most least related?

Which species is the least closely related to humans based on the comparisons of amino acids in cytochrome c?