To determine which options are NOT strengths of radio, consider the characteristics typically associated with radio as a medium:
- Audience selectivity (A): Radio can target specific demographic or interest-based audiences through different stations and time slots, which is a strength.
- Directional signage (B): This is more related to visual advertising media such as billboards or road signs, not radio. Therefore, it's not a strength of radio.
- Frequency builder (C): Radio allows frequent repetition of ads, which helps in building frequency. This is a strength of radio.
- Low cost product (D): Radio is known for its cost-effectiveness in terms of production and airtime, making it a strength.
- Low reach (E): Radio's reach, compared to other media like television or digital platforms, might be limited to certain demographics, thus it can be seen as a weakness.
Combining the analysis, the characteristics that are NOT considered strengths of radio are:
- B: Directional signage
- E: Low reach
Thus, the correct answer is (B) and (E) only.