Final answer:
During transcription, RNA polymerase uses the template DNA strand to make a complementary RNA strand, known as the + RNA strand.
Step-by-step explanation:
During transcription, an RNA polymerase uses the template DNA strand to catalyze synthesis of a complementary RNA strand. The RNA polymerase adds ribose nucleotide triphosphates (NTP) to the growing RNA strand, while incorporating uracil (U) instead of thymine (T) from the DNA. The resulting RNA strand, known as the + RNA strand, is a mobile molecular copy of the original DNA sequence.