I agree with your version of (c). However, do you really think the original doesn't work?
The National elementary principal - Page 11
by National Association of Elementary School Principals (U.S.), National Education Association of the United States. Dept. of Elementary School Principals - School principals - 1954
In music we learned many new songs
and how to read notes and do part singing.
Can we really "learn songs" but not "learn plants?"
Primitive Living, Self-Sufficiency, and Survival Skills: A Field Guide to ... - Page 104
by Thomas J. Elpel - House & Home - 2003 - 208 pages
You could take a college course in botany and learn to use a botanical key, or you could learn plants
from pictures or from people you meet. http://books.google.com/books?...%20plants%22&f=false