________ rehearsal results in a more lasting memory compared to ________ rehearsal, and promotes the transfer of information to long-term memory

According to the article Deep Roots about fetal precursors of temperament, in a correlational study, causal conclusions:

(a) can only be drawn if the correlation is very strong (b) can only be drawn if the correlation has a positive sign (c) can only be drawn if there is more than one correlation (d) can not be determined

While participating in a timed experiment, the participants in the experimental group had to leave the room because of a fire drill. Which potential threat to internal validity would this example illustrate according to Campbell and his colleagues?

a. maturation b. selection c. instrumentation d. history