Assertion (A) is true: Kent's 5th observation following the administration of a homeopathic remedy indeed describes a pattern where the patient first experiences an amelioration (improvement of symptoms) followed by an aggravation of the existing symptoms. This is considered a favorable reaction, indicating that the remedy has acted deeply and stirred up the vital force.
Reason (R) is true: The inference of Kent's 5th observation is that when the amelioration precedes the aggravation, it suggests that the remedy has acted on a deeper level. A superficial or palliative remedy typically provides only temporary relief without a subsequent stirring up of the disease symptoms. The sequence of amelioration followed by aggravation indicates that the vital force is reacting to the deeply acting remedy to expel the disease from within outwards. Therefore, the remedy is not superficial but rather acting profoundly.
Thus, both the assertion and the reason are correct, and the reason correctly explains the significance of Kent's 5th observation.