The polymer formed on heating Novolac with formaldehyde is:

We start by recalling that Novolac is a low-molecular-mass, linear phenol-formaldehyde polymer produced by the condensation of phenol with formaldehyde in the presence of an acidic catalyst. Its repeating structural unit can be written symbolically as $$\mathrm{\;-\;C_6H_4\;-\;O\;-\;CH_2\;-\;}.$$

Now, when Novolac is further heated with additional formaldehyde, the free $$\mathrm{-\;CH_2OH}$$ (methylol) groups present on the aromatic rings undergo additional condensation. Each such group can react with either the ortho or para position of a neighbouring phenol ring, forming new $$\mathrm{-\;CH_2\;-}$$ bridges and, in many places, $$\mathrm{-\;CH_2\;O\;CH_2\;-}$$ linkages. The overall set of reactions can be summarised as

$$ \mathrm{Novolac} \;+\; \text{excess formaldehyde} \;\xrightarrow[\text{heat}]{\text{(basic or acidic)}}\; \mathrm{cross\text{-}linked\;phenol\text{-}formaldehyde\;resin} $$

Because the polymer chains are now interconnected in three dimensions, the product is a hard, infusible, and insoluble thermosetting plastic. This particular cross-linked phenol-formaldehyde resin is historically known as $$\text{Bakelite}$$.

Thus, heating Novolac with formaldehyde yields Bakelite.

Hence, the correct answer is Option B.