Final answer:
The head injury in a 40-year-old man standing near a building when it exploded is MOST likely caused by primary blast injuries.
Step-by-step explanation:
The head injury in a 40-year-old man standing near a building when it exploded is MOST likely caused by A. primary blast injuries. Primary blast injuries occur due to the direct effect of the blast wave on the body, and can cause injuries such as skull fractures.