; (B) cardiovascular events; (C) head, neck, and oral cancer; (D) testicular cancer; (E) ovarian cancer; (F) transitional cell cancer; (G) motor vehicle accidents; (H) mania; (I) psychosis; (J) cognitive effects; or (K) cannabinoid hyperemesis syndrome. (b) Covered veterans In this section, the term covered veteran means a veteran who is enrolled in the patient enrollment system of the Department of Veterans Affairs under section 1705 of title 38, United States Code. (c) Long-Term observational study The Secretary may carry out a long-term observational study of the participants in the clinical trial required under subsection (a). (d) Type of cannabis In carrying out the clinical trial required by subsection (a), the Secretary shall study— (1) varying forms of cannabis, including— (A) full plants and extracts; and (B) at least three different strains of cannabis with significant variants in phenotypic traits and various ratios of tetrahydrocannabinol and cannabidiol in chemical composition; and (2) varying methods of cannabis delivery, including combustible and non-combustible inhalation and ingestion. (e) Use of control and experimental groups The clinical trial required by subsection (a) shall include both a control group and an experimental group which shall— (1) be of similar size and structure