Answer:
The correct answer is option B.
Explanation:
If a producer has patent for a product it means others cannot produce it. So, this a barrier to entry.
Similarly, in case of licensing only the producer holding license can produce. So, it is barrier to entry.
The control to a crucial input will also restrict others to produce. So, this will also be considered as a barrier.
Economies of scale is cost advantage to a firm because of its large size. It is a barrier to entry as it would discourage other new firms to enter.
Absence of economies of scale is not a barrier to entry in the product market.
