Step 1: Refractive Index:
\[ \mu=\frac{c}{v}=\frac{3\times10^8}{2\times10^8}=1.5 \]
Step 2: Normal Shift:
For a slab of thickness \(t\), viewed from above, the apparent shift is
\[ \text{shift}=t\left(1-\frac1\mu\right)=6\left(1-\frac1{1.5}\right)=6\times\frac13=2.0\ \text{cm} \]
Step 3: Check the Other Options:
3.0 cm would need \(\mu=2\), 4.0 cm would need \(\mu=3\), and 5.0 cm would need \(\mu=6\). With \(\mu=1.5\), only 2.0 cm fits.
Final Answer:
The ink dot appears raised by 2.0 cm, option (A).
\[ \boxed{\text{(A) } 2.0\ \text{cm}} \]