Phylogenetic trees compare gene or genome sequences to understand a number of aspects of the evolutionary trajectories of viruses that infect humans

Phylogenetic trees compare gene or genome sequences to understand a number of aspects of the evolutionary trajectories of viruses that infect humans, including SARS-CoV-2, the coronavirus that invaded humans in late 2019 leading to the current COVID-19 pandemic. The phylogeny below shows evolutionary relationships between viruses which have all been assigned to the coronavirus family. Explain, using this phylogenetic tree, how virologists have concluded each of the following:

a. The current SARS-CoV-2 virus causing COVID-19 in the human population most likely involved the transfer of a similar coronavirus infecting bats into humans.

b. Bat and human SARS-CoV viruses share a most recent common ancestor with MERS-CoV

c. The SARS-CoV virus causing the first epidemic of severe acute respiratory syndrome evolved the ability to infect human cells much earlier in time than the current SARS-CoV-2 virus.