To solve this question, the user needs to think critically and understand the concept of birthdays.

Option A: 78. This option is incorrect because it is an average life expectancy of a man. The question is asking about the number of birthdays a man has, not the number of years he is expected to live.

Option B: 65.5. This option is also incorrect because it is the average life expectancy of a man. It is not the number of birthdays that a man has.

Option C: one per year. This option is correct. Every person has one birthday per year. A birthday is the anniversary of a person's birth, which comes around once a year.

Option D: None. This option is incorrect. Every person has at least one birthday in their lifetime. Even if a person dies shortly after being born, they still had a birthday.

Therefore, the correct answer is:

The Answer is: C. one per year.