MICROANATOMY

Detailed explanation-1: -In practice there is considerable variation in the lifespan of human RBC. In a normal individual with a mean RBC lifespan of 115 days, this value may vary between 70 and 140 days [1, 2]. Among individuals the mean lifespan varies by approximately ±15% [1].

Detailed explanation-2: -So, the correct answer is ‘120 days’

Detailed explanation-3: -Red blood cells have a limited lifespan because they don’t have a center membrane (nucleus). When a red blood cell travels through your blood vessels, it uses up its energy supply and only survives an average of 120 days.