The correct option is D dispersed
The italicized word 'assembled' means to gather or collect. So, the opposite of the word is Option C, 'dispersed'. 'Dispersed' means scattered or distributed. Option A 'removed' means to take away or detach. Option B 'diffused' means to cause something to spread out in many directions . Option D 'eliminated' means to completely remove or get rid of. Thus, options A, B and D are incorrect and the correct option is Option C, dispersed.