<Tr> <Th_colspan="2"> Lead figures </Th> </Tr> <Tr> <Td_colspan="2"> <Table> <Tr> <Td> <P> WPC member </P> <Ul> <Li> Jo Ann Robinson </Li> </Ul> <P> MIA members </P> <Ul> <Li> Martin Luther King Jr . </Li> <Li> E.D. Nixon </Li> <Li> Rosa Parks </Li> <Li> Fred Gray </Li> </Ul> </Td> <Td> <P> City Commission </P> <Ul> <Li> W.A. Gayle, President of the Commission (mayor) </Li> <Li> Frank Parks, Commissioner </Li> <Li> Clyde Sellers, Police Commissioner </Li> </Ul> <P> National City Lines </P> <Ul> <Li> Kenneth E. Totten, vice president </Li> </Ul> <P> Montgomery City Lines </P> <Ul> <Li> J.H. Bagley, manager </Li> <Li> Jack Crenshaw, attorney </Li> <Li> James F. Blake, bus driver </Li> </Ul> </Td> </Tr> </Table> </Td> </Tr> <Table> <Tr> <Td> <P> WPC member </P> <Ul> <Li> Jo Ann Robinson </Li> </Ul> <P> MIA members </P> <Ul> <Li> Martin Luther King Jr . </Li> <Li> E.D. Nixon </Li> <Li> Rosa Parks </Li> <Li> Fred Gray </Li> </Ul> </Td> <Td> <P> City Commission </P> <Ul> <Li> W.A. Gayle, President of the Commission (mayor) </Li> <Li> Frank Parks, Commissioner </Li> <Li> Clyde Sellers, Police Commissioner </Li> </Ul> <P> National City Lines </P> <Ul> <Li> Kenneth E. Totten, vice president </Li> </Ul> <P> Montgomery City Lines </P> <Ul> <Li> J.H. Bagley, manager </Li> <Li> Jack Crenshaw, attorney </Li> <Li> James F. Blake, bus driver </Li> </Ul> </Td> </Tr> </Table> <Tr> <Td> <P> WPC member </P> <Ul> <Li> Jo Ann Robinson </Li> </Ul> <P> MIA members </P> <Ul> <Li> Martin Luther King Jr . </Li> <Li> E.D. Nixon </Li> <Li> Rosa Parks </Li> <Li> Fred Gray </Li> </Ul> </Td> <Td> <P> City Commission </P> <Ul> <Li> W.A. Gayle, President of the Commission (mayor) </Li> <Li> Frank Parks, Commissioner </Li> <Li> Clyde Sellers, Police Commissioner </Li> </Ul> <P> National City Lines </P> <Ul> <Li> Kenneth E. Totten, vice president </Li> </Ul> <P> Montgomery City Lines </P> <Ul> <Li> J.H. Bagley, manager </Li> <Li> Jack Crenshaw, attorney </Li> <Li> James F. Blake, bus driver </Li> </Ul> </Td> </Tr>

What pressure was used by the montgomery improvement association in response to segregation on buses