Boys are usually dependent on their parents . . . . . . . . they earn enough money to support themselves.

The correct answer is: A. till

The word “till” means “until”. In this sentence, it is used to indicate that boys are usually dependent on their parents until they earn enough money to support themselves.

The other options are:

• B. provided : This word means “on the condition that”. It would not make sense to say “Boys are usually dependent on their parents on the condition that they
  Join Our Telegram Channel
  288 64 288 64S117.2 64 74.6 75.5c-23.5 6.3-42 24.9-48.3 48.6-11.4 42.9-11.4 132.3-11.4 132.3s0 89.4 11.4 132.3c6.3 23.7 24.8 41.5 48.3 47.8C117.2 448 288 448 288 448s170.8 0 213.4-11.5c23.5-6.3 42-24.2 48.3-47.8 11.4-42.9 11.4-132.3 11.4-132.3s0-89.4-11.4-132.3zm-317.5 213.5V175.2l142.7 81.2-142.7 81.2z"/> Subscribe on YouTube