You can deal with gaps in an PHP array in all but one of the following ways. Which one is it? a. Use the array_values() function to remove all gaps and re-index the array. b. Use a foreach loop to process the array, which skips elements that contain nulls. c. Use a for loop that contains extra code that skips elements that contain nulls. d. Use the array_fill() function to replace all gaps in the array with empty strings