We gave Tiger swimming lessons in our plastic wading pool. I taught the kitten the way Pa taught me: I threw him into water where he could not stand, and I watched, ready to grab him if he went under. Tiger did not thrash desperately like me. He merely paddled urgently for the edge of the plastic pool with his head high and his thin legs churning. Little Bit said, "Dog paddle," and we all laughed. "Tiger paddle," I said, and we all laughed some more, even Jordy. That was probably when Ma noticed the kitten swimming lessons and stopped them. Our swimming lessons happened in two places. When Pa took us, we went to Hawkins Springs behind Mrs. DeLyons' Fountain of Youth Motor Hotel. When Ma took us, we drove to Mermaid Springs State Park, where we would sometimes meet Mr. Drake. I liked Mermaid Springs better because I felt safe there. Ma could not swim, so she never made me jump off a dock into deep water, and she always insisted that I wear an orange styrofoam cylinder on my back like a skindiver or spaceman. Ma usually sat on a towel on the grass near the beach, reading a magazine or a book while tanning her legs. Every now and then she would call to us not to go too far or not to splash each other. When she wore her one-piece red swimming suit, she would come in up to her waist, then lower herself to her shoulders, being careful not to get her hair wet. On the rarest occasions, she would wear a swimming cap and float on her back in the shallow water. Often she stayed in her shorts and shirt, adding sunglasses and removing shoes as her concession to summer and the beach. According to the above context, answer the following question. Why did Ma probably sit on a towel on the grass?

Options are: a). She liked how the towel felt against her skin. b). not enough information. c). The grass would cause her to itch, the towel made it more comfortable. d). She wanted the towel in case she swam.
The answer is:
c).