Final answer:
Mrs. Tacher's observable signs might include observed sweating and a change in voice, which are symptomatic of thyroid issues such as hypothyroidism or hyperthyroidism. An enlarged heart, while a serious condition, would not be externally observable without imaging. More context is needed for a definitive diagnosis.
Step-by-step explanation:
The observable signs Mrs. Tacher might be exhibiting include "b. observed sweating" and "e. change in voice". However, to provide a direct answer, we need more context about her specific symptoms. If Mrs. Tacher has hypothyroidism, she may exhibit signs like increased sweating, but hypothyroidism often causes weight gain rather than weight loss. A change in voice can be associated with hyperthyroidism, which also often presents with weight loss and profuse sweating.
Additionally, an enlarged heart is not typically visible from the outside and would be diagnosed through medical imaging or other tests. Hence, option "d. enlarged heart" would not be an observable sign on the outside. The remaining options, "a. protruding mandible" and "c. increase in shoe size", are not clearly related to the symptoms mentioned and would require further medical evaluation to be considered symptomatic.