To find the last digit of 237937, we only need to consider the last digit of 237, which is 7.
Therefore, we are interested in finding the last digit of 7937.
The powers of 7 follow a pattern in the last digits:
The cycle of last digits of powers of 7 is: 7, 9, 3, 1, and it repeats every 4 terms.
Now, we need to determine the position of 937 in this cycle:
\[ 937 \mod 4 = 1 \]
This means the last digit of 7937 will be the same as the last digit of 7^1, which is 7.
The last digit of 237937 is 7.
The correct answer is (d) 7.