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?
o baby b has a genetic profile that is more predisposed to ra than baby a.
o baby b has eaten a less diverse diet and not acquired health - promoting bacteria in her microbiome.
o baby b has been infected by a bacterium that causes ra.
o baby b has a microbiome consisting of species less well suited for human health.
o baby b has led a more active lifestyle, contributing to joint degeneration.

Explanation:

Rheumatoid arthritis (RA) is an autoimmune disease. Genetic factors are known to play a role in the predisposition to autoimmune diseases. If Baby B has a genetic profile more likely to lead to RA compared to Baby A, it would most likely explain why Baby B has begun to experience RA. Lifestyle factors like diet and microbiome (options 2 - 4) may contribute to overall health but are less likely to be the primary cause of a genetic - based autoimmune condition. Joint degeneration (option 1) is a different condition from RA.

Answer:

Baby B has a genetic profile that is more predisposed to RA than Baby A.