Provided following are various stages during the life of a high-mass star. rank the stages based on when they occur, from first to last.

a. contracting cloud of gas and dust
b. protostar
c. main sequence o star
d. red supergiant
e. supernova
f. neutron star

Following is the order of ranks involved in the life of a star from the beginning to end:

contracting cloud of gas and dust protostar main-sequence O star red supergiant supernova neutron star Explanation: The formation of a star begins with the accumulation of gas and dust. The stage right before the formation of an actual star is that of a protostar. In this stage, the dust and gas material comes close rapidly and finally culminates in the star formation. During the course of its life, the size of the star grows as long as it becomes a red supergiant. Towards the end of its life, there is a supernova explosion and what is finally left is known as a 'neutron star'.

2pi more meters because you find the circumference which is 6pi and 4pi and subtract it and you get 2pi