Question

because of complications during delivery of identical twins, “baby a” is born vaginally while “baby b” is born by cesarean section. as the twins have aged, baby b alone has begun to experience rheumatoid arthritis (ra). which explanation most likely accounts for the autoimmune disease endured by baby b? baby b has a genetic profile that is more predisposed to ra than baby a. baby b has eaten a less diverse diet and not acquired health - promoting bacteria in her microbiome. baby b has been infected by a bacterium that causes ra. baby b has a microbiome consisting of species less well suited for human health. baby b has led a more active lifestyle, contributing to joint degeneration.

Explanation:

Identical twins have the same genetic makeup. Lifestyle - related factors like diet and microbiome composition can influence the development of autoimmune diseases. A less diverse diet may lead to a less - optimal microbiome and increase the risk of autoimmune conditions like RA. While there is no known single bacterium that causes RA, an imbalanced microbiome can contribute to immune dysregulation. Joint degeneration from an active lifestyle is different from an autoimmune disease mechanism. So, a less diverse diet and sub - optimal microbiome is a likely explanation.

Answer:

Baby B has eaten a less diverse diet and not acquired health - promoting bacteria in her microbiome.