Explanation:

- Applications of Ultrasound:

- Detect cracks and flaws in metal blocks: Ultrasound waves are widely used in industrial settings to find inconsistencies in metal integrity.

- Echocardiography: This medical imaging technique uses ultrasound waves to create images of the heart, allowing for detailed heart function assessment.

- Treatment of Kidney Stones: Known as lithotripsy, ultrasound waves can break down kidney stones into smaller, passable pieces.

- Cleaning of odd-shaped objects: Ultrasound waves efficiently clean complex surfaces by loosening debris and contaminants.

- Option Analysis:

- Option 1 - Only 1 & 2: Excludes important applications such as lithotripsy and cleaning.

- Option 2 - Only 1, 2 & 3: Correct, but misses ultra-cleaning uses.

- Option 3 - Only 1, 3 & 4: Leaves out echocardiography.

- Option 4 - 1, 2, 3 & 4: Correct, as all listed applications are valid uses of ultrasound.

- The correct answer is 1, 2, 3 & 4 from Option 4.