Cracking the Logic
The key to solving this puzzle lies in recognizing that a person's age in years does not always equal the number of calendar birthdays they have celebrated. Jennifer was born on a Leap Day—February 29th.
Because a leap year occurs only once every four years, an individual born on this day only experiences a literal calendar birthday once every quadrennial cycle.
If Jennifer celebrated her 26th actual birthday on February 29th, we multiply her birthdays by the four-year cycle: $26 \times 4 = \mathbf{104}$. Therefore, Jennifer was actually 104 years old when she passed away, beautifully satisfying the condition of being at a "very old age."