Answer: Replication forks
Step-by-step explanation:
A DNA replication bubble forms at a specific sequence of bases called the replication forks.
A specific protein recognises the origin and bind to a particular site and opens the DNA strands. As the DNA strands opens in a Y-shaped structures called replication forks and togetehr they form replication bubble.
The replication forks then starts moving in opposite direction as the replication proceeds. Then the helicase enzyme initiates the process of replication.
Hence, A DNA replication bubble forms at a specific sequence of bases called the r.eplication forks.