Final answer:
Since about 1974, music therapy has become increasingly recognized and formalized, leading its use in health care settings to grow significantly. Although music has historically been used for healing, the establishment of professional organizations like the American Music Therapy Association in 1998 marks a notable increase in standardized practice and research in music therapy.
Step-by-step explanation:
In the context of music therapy, the usage of music in health care settings since about 1974 has evolved significantly. It was around this time that the professional discipline of music therapy began to be more formally established, with the American Music Therapy Association (AMTA) being founded in 1998 as a merger of earlier associations. Option B suggests that it started being used, which corresponds with the idea that the formal recognition and structured application of music therapy took on greater significance in the 1970s. However, music has been used for healing purposes in various forms throughout history, so it's also accurate to say that its therapeutic use was already prevalent to some extent prior to this period.
The formal recognition helped to standardize the practice, research, and education in music therapy, leading to its wider adoption in health care facilities. It is well-documented that since the mid-1970s, music therapy has been increasingly incorporated into health care settings, due to its non-invasive nature and its ability to positively affect mood, reduce stress, manage pain, and improve cognitive functioning among other benefits.