Choose all statements that accurately describe the transcription bubble.
a. it moves along the dna at a rate of about 50 nt/sec it is stationary, with the dna strand slowly threaded through it at a rate of about 50 nt/sec
b. the growing rna strand protrudes from the bubble it contains an rna-dna hybrid, about 9 nt long
c. the newly made rna within the bubble makes a single nucleotide contact with dna at the 3' end
d. the growing rna is compacted it within a specialized compartment inside the bubble

Option A and Option B

Explanation:

A transcription bubble is defined as  a molecular structure which is formed when only a few or very limited section of the DNA strand has unwind-ed.

These transcription bubbles are small in size and  in general their size ranges between 12-14 base pairs

An RNA polymerase which is about 9 nt long is responsible for making the DNA sequence ready for producing transcript at the 5' end (a complementary, antiparallel RNA strand )

Rate at which  double stranded DNA molecule slide back and forth for transcription ranges with in 40-50 nt/sec

Hence, both option A and B are correct