Final answer:
Inhibiting enzymes involved in transcription initiation and elongation would decrease the rate of transcription or potentially stop it altogether due to interference with RNA polymerase function and transcription factor binding.
Step-by-step explanation:
The effect of inhibiting the access of enzymes involved in transcription initiation and elongation to DNA is to decrease the rate of transcription or stop it completely. In transcription initiation, RNA polymerase binds to the promoter region, signaling for the DNA to unwind for transcription to begin. During elongation, RNA polymerase reads the DNA strand and adds nucleotides to the growing mRNA strand. If inhibitors, such as Actinomycin-D, interfere with these processes, they can prevent the movement of RNA polymerase along the DNA template, leading to jamming of the enzyme and a halt in transcription. Moreover, binding of transcription factors to enhancer regions aids in the recruitment of RNA polymerase, thus leading to increased transcription. Inhibition of these processes could prevent transcription factors from properly functioning, again leading to decreased transcription. Therefore, the correct answer is 2) It decreases the rate of transcription or 4) It stops transcription completely.