Answer:
b. enter into a joint venture to protect the product
Step-by-step explanation:
First Mover is the big initiator of a new product, which gains a competitive 'first mover advantage' for being the pioneer of the idea in the market.
When a first mover doesn't have complementary assets, the barriers to imitation are high, and there are several capable competitors : It implies that there is huge unfulfilled demand in the market, which can't be satisfied by the desiring competitors through illegitimate imitation. But, the competitors desiring to enter can be leveraged to procure, provide for the complementary asset the 'first mover' firm is lacking. This can be done by entering into a joint venture with them.
It would lead to expansion - due to complementary asset access, also protect the product.