Hi kamalakarthi,

Based on the answer that you chose, I think that you understood what the sentence was trying to communicate. The issue here is more about "Efficiency" than anything else. GMAT SCs almost always remove redundancy and find the "short way" to communicate ideas (there are some exceptions, of course, but they're usually tied to some other grammar rule - such as Parallelism).

Here, the idea is that Ansel Adams started photographing Yosemite when he was a teenager and then kept photographing it. However, what I just typed is WORDY and not the "short way" to communicate the idea. The more efficient way is to state that Ansel Adams photographed Yosemite from his teenage years on.

GMAT assassins aren't born, they're made,
Rich