Final answer:
A stiff vertical support in timber framing is known as a post (option c), which serves as an essential load-bearing element within the post-and-lintel construction method.
Step-by-step explanation:
The correct answer to the question "What is a stiff vertical support, especially a wooden column in timber framing?" is c) Post. In the context of timber framing, a post is a strong, vertical support that can be made of wood. It is a crucial part of the post-and-lintel construction method, which uses a horizontal beam (lintel) placed over a void, supported at its ends by the posts. This system has been employed since ancient times and remains in use today due to its simplicity and effectiveness. For example, in medieval wooden churches like the stave churches, load-bearing posts (stafr in Old Norse) were essential for the longevity of these structures.
It's important to distinguish a post from decorative elements such as a pilaster, which may resemble a column but doesn't actually bear a load. In Romanesque architecture, real columns were used alongside pilasters and varied in material and style. The post is the functional vertical support without which structures would lack stability and strength.