To identify characteristics that are NOT strengths of radio, evaluate the typical attributes of radio as a medium:
- Audience selectivity (A): Radio's ability to target specific demographics or interest groups via different stations and time slots is a strength.
- Directional signage (B): This characteristic is associated with visual media like billboards, not radio. Consequently, it is not a strength of radio.
- Frequency builder (C): Radio enables frequent ad repetition, which is effective for building frequency and is therefore a strength.
- Low cost product (D): Radio is recognized for its cost-effectiveness in both production and airtime, making it a strength.
- Low reach (E): Radio's reach, potentially limited to certain demographics compared to other media such as television or digital platforms, can be considered a weakness.
Based on this analysis, the characteristics that are NOT strengths of radio are:
- B: Directional signage
- E: Low reach
Therefore, the correct answer is exclusively (B) and (E).