Final answer:
Complexity of an innovation can negatively affect product acceptance, as it can discourage potential users due to its difficulty in use or understanding.
Step-by-step explanation:
Among the characteristics of an innovation that could impact the acceptance of a product in the intended market, Complexity is likely to have a negative impact. Complexity refers to how difficult the innovation is to understand and use. If a product is too complex, potential users might be discouraged from adopting it because they may find it hard to learn how to use it or to understand its benefits.
The other characteristics listed - Relative advantage, Compatibility, Trialability, and Observability - generally have a positive effect on the adoption of an innovation.