a question of time
Meaning: You can say “it’s only a question of time” before saying what you think will happen in the future.
- It’s only a question of time until we run out of oil, so we’re going to need other forms of energy to power our cars.
- If you keep on spending money like this, it’ll just be a question of time before you have a serious debt problem.
Note: This idiom is almost always used with the word “only” or with the word “just”, as in “It’s only a question of time before … ” or “It’s just a question of time.”
the answer is: b