**Core Concept:**
The general fertility rate (GFR) is a demographic statistic calculated as the number of live births per 1,000 women of childbearing age (15-49 years) in a given year. It is expressed as:

GFR = (Number of live births / Total female population aged 15-49 years) * 1,000

**Why the Correct Answer is Right:**
The denominator of the general fertility rate equation represents the female population of childbearing age (15-49 years). In this context, the correct answer is:

D. Total female population aged 15-49 years

**Why Each Wrong Option is Incorrect:**
A. 15-14 years or 49-50 years: These options are incorrect because they do not represent the specific age range considered for the fertile population in calculating GFR.
B. Total female population: This option is incorrect because the denominator should be the fertile population (15-49 years) rather than the total female population.
C. 15-49 years * 2: This option is incorrect because multiplying the age range by 2 would result in an incorrect denominator and thus an incorrect GFR calculation.

**Why the Correct Answer is Right:**
In calculating the GFR, the denominator should represent the female population that is most likely to give birth. In this case, we consider the female population between 15 and 49 years old because this age group is more likely to be sexually active and have children.

**Clinical Pearl:**
The general fertility rate is an important indicator of a country's reproductive health and demographic trends. It can help policymakers and healthcare providers understand fertility patterns, plan family planning programs, and allocate resources accordingly.