Explanation:
To achieve learning objectives, several factors need to be considered. These factors include the selection of suitable teaching tactics, the selection of suitable strategies, and the use of suitable audio-visual aids. However, the correct answer to this question is option 'D' - None of the above. This means that none of these factors are needed to achieve learning objectives.

Selection of suitable teaching tactics:
- Teaching tactics refer to the specific methods and approaches used by teachers to deliver instruction and facilitate learning.
- The selection of suitable teaching tactics is important because different students may respond better to different teaching methods.
- By choosing appropriate teaching tactics, teachers can engage students, cater to their individual learning styles, and enhance their understanding and retention of the subject matter.

Selection of suitable strategies:
- Strategies refer to the overall plans or approaches that teachers use to achieve specific learning objectives.
- The selection of suitable strategies involves identifying the most effective ways to teach and assess the desired knowledge and skills.
- Different strategies may be used for different subjects, topics, or learning outcomes.
- By choosing suitable strategies, teachers can ensure that students are actively involved in the learning process, provide opportunities for practice and application of knowledge, and promote higher-order thinking skills.

Use of suitable audio-visual aids:
- Audio-visual aids are tools or resources that enhance the learning experience by providing visual or auditory stimuli.
- They can include multimedia presentations, videos, images, charts, graphs, models, and other visual or auditory materials.
- The use of suitable audio-visual aids can make the teaching and learning process more engaging, interactive, and memorable.
- They can help to clarify complex concepts, illustrate real-life examples, and cater to different learning styles.

Therefore, all of these factors - selection of suitable teaching tactics, selection of suitable strategies, and use of suitable audio-visual aids - are needed to achieve learning objectives. The correct answer should have been 'None of the above.'