<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:Fluorescein is an artificial dark orange colored organic molecule used in the diagnosis of corneal ulcers and herpetic corneal infections. It is observed that, in experimental animals, the fluorescein binds to receptors on certain B cells, but it does not stimulate them to produce fluorescein specific antibodies unless it is first attached to a larger molecule such as albumin. Which of the following terms best describes fluorescein?? A: Carrier, B: Hapten, C: Tolerogen, D: Adjuvant, E: Immunogen,  <response>: This is a question about the properties of fluorescein and how it interacts with the immune system. Fluorescein is a small organic molecule that can bind to receptors on B cells but does not stimulate antibody production on its own. It requires attachment to a larger carrier molecule like albumin to become immunogenic. Based on this information, fluorescein is best described as a hapten - a small molecule that can elicit an immune response only when attached to a carrier.B: Hapten 