Skateboarding is a type of activity covered by the primary assumption of risk doctrine. An activity falls within that doctrine if " 'the activity is done for enjoyment or thrill, requires physical exertion as well as elements of skill, and involves a challenge containing a potential risk of injury.' " (Bjork v. Mason (2000) 77 Cal. App. 4th 544, 550 92 Cal. Rptr. 2d 49; Record v. Reason (1999) 73 Cal. App. 4th 472, 482 86 Cal. Rptr. 2d 547.) These factors certainly apply to skateboarding. "As a general rule, each person has a duty to use ordinary care and 'is liable for injuries caused by his or her failure to exercise reasonable care in the circumstances . . . .' (Rowland v. Christian (1968) 69 Cal. 2d 108, 112 70 Cal. Rptr. 97, 443 P.2d 561.)" (Parsons v. Crown Disposal Co. (1997) 15 Cal. 4th 456, 472 63 Cal. Rptr. 2d 291, 936 P.2d 70 (Parsons).) The scope of this duty of care, however, is limited in the context of active sports. (See Knight v. Jewett (1992) 3 Cal. 4th 296 11 Cal. Rptr. 2d 2, 834 P.2d 696.) Under the primary assumption of risk doctrine, there is no duty to eliminate or protect a plaintiff against risks that are inherent in a sport or activity. (Id. at pp. 315-316.)