Which of the following is the only drug is found to be beneficial in halting the progression on EDSS of multiple sclerosis:

Ans is 'c' i.e. Natalizumab o EDSS (Expanded disability status scale) is a method of quantifying disability in multiple sclerosis. o EDSS steps 1.0 to 4.5 refer to people with MS who are fully ambulatory. EDSS steps 5.0 to 9.5 are defined by the impairment in amubulation. EDSS 10 is defined as death due to MS. o Natalizumab silences disease activity and rapidly improves disability status and walking performance, possibly through delayed relapse recovery in patients with RRMS who had shown a high level of disease activity under other disease modifying drugs for multiple sclerosis.