Baeza (2008) Studied a Symbiotic Shrimp (Pontonia Margarita) That Lives

Baeza (2008) studied a symbiotic shrimp (Pontonia margarita) that lives inside the mantle cavity of the pearl oyster (Pinctada mazatlanica) . One of his findings was that body sizes of shrimp and host oysters were closely correlated, suggesting that particular associations are long lasting. These data were consistent with social (and perhaps, genetic) monogamy in the shrimp. What other aspect(s) of the shrimps' life style would support that conclusion?

A) If there were two shrimp per host, they were always a male and a female.
B) The oyster hosts are small in size and are rare.
C) The shrimp live in predator-rich waters and would be especially vulnerable when away from their host.
D) all of the above.