According to the IMO Performance Standards incorporated in 33 CFR §164.38, what is the minimum number of targets an ARPA with automatic acquisition must be capable of tracking simultaneously?

Why C is correct

33 CFR §164.38, Appendix A, paragraph 3.3.1 states that if automatic acquisition is provided, the ARPA must automatically track, process, display, and continuously update information on at least 20 targets. The 10-target minimum applies only when manual acquisition is the sole method provided.