<prompt> Longest life span among following -RBCPlalaletsNeutrophilsMacrophages  <response>: Ans. is d i.e., Macrophages Life span of blood ceilsRBC: 120 daysPlatelets : 7-12 daysMonocytes in circulation : 1-3 daysMacrophages in tissues : Months-yearsNeutrophils in circulation : 4-8 hrsNeutrophils in tissue : 2-5 daysShort lived lymphocytes : 2 weeksLong lived lymphocytes : Upto 3 years 