Answer:
A. The RNA polymerase subunits of the P.syringae strain probably have extra flexibility so that they can move more freely in colder temperatures.
Step-by-step explanation:
Because there is no difference in the amount of the RNA polymerases but rather their activity, the difference lies in their structure and not their sequence. Hence the answer can't be (B) or (D). Adaptations are made to broaden the conditions of survival. Hence E. coli would not limit it's survival by limiting its growth to warmer temperatures. Hence the answer is (A) the RNA polymerase subunits of the P. syringae strain probably have extra flexibility so that they can move more freely in colder temperatures.