Question 50: Mark the letter A, B, C or D to indicate the correct answer to each of the following question: 53. In most countries, driving tests are available on_______.

Answer A

Explanation: on demand (idm): anytime you want or need

The remaining answers:

requesting (Ving): asking for question (n): question

asking (Ving): asking

In most countries, the driving test is available whenever needed.