Given a variable named userID, which of the following statements prints a debug message to the LogCat view that displays the value of the userID variable?
a. Log.e("userID: ", userID);
b. Log.d("userID: " + userID);
c. Log.e(TAG, "userID: " + userID);
d. Log.d(TAG, "userID: " + userID);
Answer: D