The word ‘smog’ is derived from ‘smoke’ and ‘fog’. There are two kinds of smog and only one involves smoke and fog. The one that does is called sulphurous smog, also called “London smog”. It happens when there is a high concentration of sulphur oxides in the air (the smoke) and results from the burning of sulphur-bearing fossil fuels, especially coal. This kind of smog is exacerbated by dampness and high concentrations of suspended particulate matter in the air (the fog). This no longer occurs in many places due to “clean air” legislation which has reduced the burning of coal.
The other kind of smog, more common these days, is petrochemical smog, which is also known as “Los Angeles smog”. This smog results from nitrogen oxides and hydrocarbon vapours, which are mainly emitted by cars. These compounds undergo photochemical reactions in the lower atmosphere. A product formed is the highly toxic gas ozone.
As the latter is the more common form of smog encountered these days the answer to your question is none of the options you give. It is mainly gaseous.