An ARPA installed pursuant to 33 CFR §164.38 must be capable of simultaneously tracking and displaying continuously updated information on at least how many targets when only manual acquisition is provided?

Why A is correct

33 CFR §164.38, Appendix A, paragraph 3.3.1 states the ARPA must track at least 20 targets if automatic acquisition is provided, or at least 10 targets if only manual acquisition is provided. The 20-target figure applies only when automatic acquisition is available.