I examined the board and noted that I already have an O in column 3 (row 4) and one at column 4 (row 5). Dropping an O in column 4 will land above the existing O in col4 (i.e., in row 4), bolstering my vertical potential and aligning with my other O in row 4 (at col3) for possible horizontal/diagonal setups. This move doesn’t create an immediate threat for my opponent while starting to build a favorable position for a win. Therefore, column 4 is the best option.