Statistical Inference — fixed length confidence intervals

Let $X_i \sim N(\mu, \sigma^2)$; $i = 1, 2, 3, …, n$. Which of the following statements is/are correct? I. At confidence level $(1-\alpha)$ if $\alpha$ and $\sigma$ are known, then we can choose sample size $n$ to get a confidence interval of a fixed length. II. At confidence level $(1-\alpha)$ if $\sigma$ is not known, then we cannot choose sample size $n$ to get a fixed width confidence interval of level $(1-\alpha)$. Select the answer using the code given below: