With no explanation, chose the best option from "A", "B", "C" or "D". law enforcement objectives, and the concomitant need for the courts to maintain vigilance, is a recurrent theme in our cases and those of other courts. In United States v. Schafer, 461 F.2d 856 (9th Cir.), cert. denied, 409 U.S. 881, 93 S.Ct. 211, 34 L.Ed.2d 136 (1972), for example, we upheld the admission of evidence inadvertently discovered during a routine agricultural quarantine search, but were careful to note that “[n]othing in the record suggests that the administrative search in this case was ‘employed as an instrument of criminal law enforcement to circumvent the latter’s legal restrictions....’” Id. at 859 (quoting Abel v. United States, 362 U.S. 217, 230, 80 S.Ct. 683, 692, 4 L.Ed.2d 668 (1960)). See also United States v. Pulido-Baquerizo, 800 F.2d 899, 902 (9th Cir.1986) (<HOLDING>) (emphasis added); United States v. Epperson,

A: recognizing the courts continued holding that visual observation is no search at all
B: holding that defendants consent to a search of their luggage was undermined by officers misrepresentation that a drug dog had alerted to their luggage
C: holding that a canine sniff of luggage does not constitute a search
D: holding that a visual inspection and limited hand search of luggage which is used for the purpose of detecting weapons or explosives and not in order to uncover other types of contraband is a privacy intrusion we believe free society is willing to tolerate
D.