Albert felt that ‘the medical certificate was burning a hole in his pocket’ because both option (A) and (B) were true. Let's discuss each of these reasons in detail:

a) It had cost him money:
When Albert says that the medical certificate was burning a hole in his pocket, it implies that he felt it was a waste of money. Obtaining a medical certificate usually involves paying a fee, whether it's for a doctor's consultation or for conducting medical tests. In Albert's case, he may have spent money to get the certificate, but it ended up being of no use to him. This can be frustrating because he essentially wasted his hard-earned money on something that did not serve its purpose.

b) It proved to be of no use:
Albert might have needed the medical certificate for a specific purpose, such as providing it to his employer, school, or any other institution that required proof of his medical condition. However, despite having the certificate, it did not serve its intended purpose. This could be because the recipient did not accept the certificate, did not find it valid, or simply did not require it.

c) Both (A) and (B):
Since both reasons (a) and (b) are true, option (C) is the correct answer. Albert not only wasted money on obtaining the medical certificate but also faced disappointment when it did not serve the purpose for which it was obtained. The phrase "burning a hole in his pocket" suggests that Albert felt the negative impact of his investment in the certificate, both emotionally and financially.

In conclusion, Albert felt that the medical certificate was burning a hole in his pocket because it cost him money and proved to be of no use. This combination of financial loss and disappointment likely led to his frustration and dissatisfaction.