The value of z used in a confidence interval depends on the desired level of confidence. In this case, the confidence level is given as 93%.

1. Determining the Confidence Level:
The confidence level is the probability that the true population parameter lies within the confidence interval. In this case, the confidence level is 93%.

2. Finding the Critical Value:
To find the critical value of z for a given confidence level, we need to look up the corresponding value in the standard normal distribution table. The z-value represents the number of standard deviations away from the mean.

3. Using the Standard Normal Distribution Table:
Looking up the z-value for a 93% confidence level in the standard normal distribution table, we find that the z-value is approximately 1.81.

4. Choosing the Correct Option:
Comparing the calculated z-value of 1.81 with the given options, we can see that option 'A' is the only one that matches.

Therefore, the correct answer is option 'A' (1.81).

The z-value represents the number of standard deviations away from the mean and is used to calculate the margin of error in a confidence interval. A larger z-value corresponds to a wider confidence interval, indicating a lower level of precision in estimating the population parameter.

By using the calculated z-value of 1.81, we can construct a 93% confidence interval by taking the sample mean and adding/subtracting the margin of error determined by the z-value.