Step 1: Recall the formula for apparent depth.
The apparent depth (\( d_{\text{apparent}} \)) is related to the real depth (\( d_{\text{real}} \)) and the refractive index (\( n \)) of the medium by the formula:
\[ d_{\text{apparent}} = \frac{d_{\text{real}}}{n}. \]
Step 2: Substitute the given values.
The real depth of the tank is \( d_{\text{real}} = 4 \, \text{m} \), and the refractive index of water is \( n = \frac{4}{3} \). Substituting these values:
\[ d_{\text{apparent}} = \frac{4}{\frac{4}{3}} = 4 \cdot \frac{3}{4} = 3 \, \text{m}. \]
Final Answer: The bottom of the tank appears to be at a depth of \( \mathbf{3 \, \text{m}} \), which corresponds to option \( \mathbf{(1)} \).