c. abab
The rhyme scheme is the pattern of rhyme in a poem. In order to determine the rhyme scheme, you really only need to pay attention to the last word of each line: bower, mingle, flower, dingle. The first line is labeled with the first letter of the alphabet (A). Any lines that rhyme with the first line also end in A. Since bower and flower rhyme, they are both labeled A. The next line that doesn't rhyme receives the next letter of the alphabet: B. Since bower and mingle do not rhyme, mingle is labeled B. Mingle does rhyme with dingle, so it also is labeled B. Therefore the rhyme scheme is
bower A
mingle B
flower A
dingle B
ABAB