Why are formulas used in spreadsheets? A to ensure that data is entered correctly
B so that calculations are automatically redone when data is changed
C to ensure that data is properly formatted
D so that errors can be easily identified when data is changed.

The answer to this question is given below in the explanation section.

Explanation:

The correct answer to this question is B.

The formulas in the spreadsheet are used to do the automatic calculation when data is changed in the spreadsheet.

For example, if you add numbers in a column and then get average. you can use sum() and average() formula to calculate the sum and average of numbers in a column. If you will change any number in the column, the calculation for sum and average automatically done. So, the answer to this question is B. i.e.

so that calculations are automatically redone when data is changed.

While the other options are not correct because:

which of the following is not an effect of technology on farming?

the correct answer is: it makes farmers perform more tasks by hand for apex.