During an endocrinology lecture, a professor explains why thyroxine remains in the bloodstream longer than triiodothyronine. Which feature best accounts for this difference?

Thyroxine is secreted only during stress, whereas triiodothyronine is released continuously.

Thyroxine binds less strongly to plasma proteins, causing slower tissue uptake.

Thyroxine has a longer half-life and mainly serves as a circulating precursor that can be converted into the more active triiodothyronine.

Thyroxine contains fewer iodine atoms, making it less susceptible to enzymatic breakdown.