Final answer:
Brazing and soldering primarily allow the joining of dissimilar metals using a filler material which has a lower melting point than the base metals, with the solidified filler creating the joint.
Step-by-step explanation:
Brazing and soldering are both processes that allow the joining of materials, commonly metals, without melting the base materials. Specifically, the correct answer to what brazing and soldering allow is B. Joining of dissimilar metals. These techniques involve the use of a filler material that has a lower melting point than the base materials. The filler metal flows into the joint by capillary action and is then solidified to form a bond between the pieces.
While brazing and soldering can sometimes provide higher joint strength compared with some forms of adhesive bonding, they are not typically used when maximum joint strength is required, as seen with welding. Therefore, the option of higher joint strength is not the primary function of these processes. Faster cooling times and deeper penetration are also more characteristic of other processes, like welding, rather than brazing and soldering.