Ascientist wants to test whether the ph, salinity, and temperature of seawater impacts coral development. he sets up an experiment with three conditions: aquarium 1: normal ph, normal salinity, normal temperature aquarium 2: high ph, high salinity, high temperature aquarium 3: low ph, low salinity, low temperature he finds that coral grow the least in aquarium 2. he concludes that coral does not grow well in conditions with high salt. why is this an invalid conclusion?