Correct Answer: Modern

Solution : The correct choice is the second option.

The word ancient refers to something very old or belonging to a former period. Its opposite is modern , which pertains to the current or contemporary period. In the given context, the patient was happy to receive treatments based on ancient methods, so the opposite, or antonym, would be treatments based on modern methods.

The meanings of the other options are as follows:

• Multiple means having or involving many parts, elements, or members.
• Slow means moving or operating at a low speed, not quick or fast.
• Primitive means denoting or preserving the character of an early stage in the evolutionary or historical development of something.